Rotorcraft-assisted system and method for launching and retrieving a fixed-wing aircraft into and from free flight

ABSTRACT

Various embodiments of the present disclosure provide a rotorcraft-assisted system and method for launching and retrieving a fixed-wing aircraft into and from free flight. The launch and retrieval system includes a modular multicopter, a storage and launch system, an anchor system, a flexible capture member, and an aircraft-landing structure. The multicopter is attachable to the fixed-wing aircraft to facilitate launching the fixed-wing aircraft into free, wing-borne flight. The storage and launch system is usable to store the multicopter (when disassembled) and to act as a launch mount for the fixed-wing aircraft by retaining the fixed-wing aircraft in a desired launch orientation. The anchor system is usable with the multicopter, the flexible capture member, and the aircraft-landing structure to retrieve the fixed-wing aircraft from free, wing-borne flight.

PRIORITY CLAIM

This patent application claims priority to and the benefit of U.S.Provisional Patent Application No. 62/376,359, which was filed on Aug.17, 2016, the entire contents of which are incorporated herein byreference.

BACKGROUND

Aircraft capable of long-distance, efficient cruising flight typicallyrequire long runways for take-off and landing. This limits the locationsfrom which the aircraft can take-off and at which the aircraft can land,since many locations don't have sufficient space for a runway. There isa need for new systems and methods that eliminate the need for theseaircraft to use long runways to take-off and land.

SUMMARY

Various embodiments of the present disclosure provide arotorcraft-assisted system and method for launching and retrieving afixed-wing aircraft into and from free flight (sometimes called the“launch and retrieval system” for brevity).

The launch and retrieval system includes a modular multicopter, astorage and launch system, an anchor system, a flexible capture member,and an aircraft-landing structure. The multicopter is attachable to thefixed-wing aircraft to facilitate launching the fixed-wing aircraft intofree, wing-borne flight. The storage and launch system is usable tostore the multicopter (when disassembled) and to act as a launch mountfor the fixed-wing aircraft by retaining the fixed-wing aircraft in adesired launch orientation. The anchor system is usable with themulticopter, the flexible capture member, and the aircraft-landingstructure to retrieve the fixed-wing aircraft from free, wing-borneflight.

Generally, to launch the fixed-wing aircraft into free, wing-borneflight, an operator (or operators): (1) removes the disassembledmulticopter from a container of the storage and launch system; (2)assembles the multicopter; (3) mounts the fixed-wing aircraft to alaunch-assist assembly of the storage and launch system, which retainsthe fixed-wing aircraft in a desired launch orientation; (4) attachesthe multicopter to the fixed-wing aircraft; (5) controls the multicopterto lift the fixed-wing aircraft to a desired altitude and to accelerateto a desired speed; (6) controls the multicopter to release thefixed-wing aircraft into free, wing-borne flight; and (7) controls themulticopter to land.

Generally, to retrieve the fixed-wing aircraft from free, wing-borneflight, an operator (or operators): (1) attaches a free end of theflexible capture member to the multicopter such that the flexiblecapture member extends from a drum of the anchor system through theaircraft-landing structure to the multicopter; (2) inflates theaircraft-landing structure such that it is positioned above the anchorsystem; (3) controls the multicopter to fly to a designated altitudeabove the anchor system and to station-keep relative to the anchorsystem such that the flexible capture member extends therebetween andthe anchor system regulates the tension in the flexible capture member;(4) controls the fixed-wing aircraft to contact and capture the flexiblecapture member; (5) controls the multicopter to descend such that thefixed-wing aircraft contacts the aircraft-landing structure and a groundcrew can secure the fixed-wing aircraft; and (6) controls themulticopter to land.

Additional features and advantages of the present disclosure aredescribed in, and will be apparent from, the following DetailedDescription and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a top perspective view of one example embodiment of themulticopter of the present disclosure attached to a fixed-wing aircraft.

FIG. 1B is a top plan view of the multicopter and the fixed-wingaircraft of FIG. 1A.

FIG. 1C is a top perspective view of the multicopter of FIG. 1A.

FIG. 1D is a bottom perspective view of the multicopter of FIG. 1A.

FIG. 1E is a partially exploded top perspective view of the multicopterof FIG. 1A.

FIG. 1F is a partially exploded bottom perspective view of themulticopter of FIG. 1A.

FIG. 1G is a block diagram showing certain electrically controlledcomponents of the multicopter of FIG. 1A.

FIG. 2A is a top perspective view of the hub module of the multicopterof FIG. 1A.

FIG. 2B is a bottom perspective view of the hub module of FIG. 2A.

FIG. 2C is a partially exploded top perspective view of the hub moduleof FIG. 2A showing the hub base separated from the saddle.

FIG. 3A is a top perspective view of the hub base of the hub module ofFIG. 2A.

FIG. 3B is a bottom perspective view of the hub base of FIG. 3A.

FIG. 3C is a partially exploded top perspective view of the hub base ofFIG. 3A.

FIG. 3D is an exploded top perspective view of the supports andassociated mounting hardware of the hub base of FIG. 3A.

FIG. 3E is an exploded top perspective view of the isolator plate andassociated mounting hardware of the hub base of FIG. 3A.

FIG. 3F is a partial cross-sectional view of one of the isolator platemounts of the hub base of FIG. 3A taken substantially along line 3F-3Fof FIG. 3C.

FIG. 3G is a partially exploded top perspective view of one of thefemale blind mate assemblies of the hub base of FIG. 3A.

FIG. 3H is a partial cross-sectional view of one of the flexural mountsof the female blind mate assembly of FIG. 3G taken substantially alongline 3H-3H of FIG. 3C.

FIG. 4A is a top perspective view of the saddle of the hub module ofFIG. 2A.

FIG. 4B is a bottom perspective view of the saddle of FIG. 4A.

FIG. 4C is a partially exploded top perspective view of the saddle ofFIG. 4A.

FIGS. 4D and 4E are side elevational views of the saddle of FIG. 4Ashowing different positions of the saddle.

FIG. 4F is a top perspective view of the cam of the saddle of FIG. 4A.

FIG. 4G is an exploded top perspective view of the aircraftattaching/releasing assembly and the cam of the saddle of FIG. 4A.

FIG. 4H is a partial cross-sectional view of the saddle of FIG. 4A takensubstantially along line 4H-4H of FIG. 4C showing the cam in an attachedrotational position.

FIG. 4I is a partial cross-sectional view of the saddle of FIG. 4A takensubstantially along line 4H-4H of FIG. 4C showing the cam in a releaserotational position.

FIG. 5A is a top perspective view of one of the rotor arm modules of themulticopter of FIG. 1A.

FIG. 5B is a bottom perspective view of the rotor arm module of FIG. 5A.

FIG. 5C is a top perspective view of the locking assembly of the rotorarm module of FIG. 5A.

FIGS. 5D, 5E, and 5F are side elevational views of the rotor arm moduleof FIG. 5A detaching from the hub module of FIG. 2A via the lockingassembly of FIG. 5C.

FIG. 5G is an exploded top perspective view of one of the rotor armassemblies and part of the rotor assembly of the rotor arm module ofFIG. 5A.

FIG. 5H is a cross-sectional view of the rotor motor assemblies of therotor arm module of FIG. 5A taken substantially along line 5H-5H of FIG.5A.

FIG. 5I is an exploded top perspective view of one of the rotor motorcollars and one of the rotor motor fans of the rotor arm module of FIG.5A.

FIG. 5J is a cross-sectional view of the rotor assembly of the rotor armmodule of FIG. 5A taken substantially along line 5J-5J of FIG. 5A.

FIG. 6A is a top perspective view of one of the front landing gearextension modules of the multicopter of FIG. 1A.

FIG. 6B is a top perspective view of one of the rear landing gearextension modules of the multicopter of FIG. 1A.

FIG. 7A is a top perspective view of one of the front landing gearmodules of the multicopter of FIG. 1A.

FIG. 7B is a top perspective view of one of the rear landing gearmodules of the multicopter of FIG. 1A.

FIG. 8A is a partially exploded top perspective view of the multicopterof FIG. 1A stored in one example embodiment of the storage and launchsystem of the present disclosure.

FIG. 8B is an exploded top perspective view of the storage and launchsystem of FIG. 8A, the 13 modules of the multicopter of FIG. 1A, andelements used to store the multicopter.

FIG. 8C is a top perspective view of the launch-assist assembly of thestorage and launch system of FIG. 8A in the launch position.

FIG. 8D is a top perspective view of the storage and launch system ofFIG. 8A with the fixed-wing aircraft mounted thereto.

FIG. 8E is an exploded top perspective view of the fuselage-retainingassembly of the launch-assist assembly of FIG. 8C.

FIG. 8F is a front elevational view of the fuselage-retaining assemblyof FIG. 8E.

FIG. 8G is a back elevational view of the fuselage-retaining assembly ofFIG. 8E.

FIG. 8H is a top perspective view of the rotor arm module and rearlanding gear module storage device of the present disclosure.

FIG. 8I is a cross-sectional view of the rotor arm module and rearlanding gear module storage device of FIG. 8H taken substantially alongline 8I-8I of FIG. 8H.

FIG. 8J is a top perspective view of the hub module storage tray of thepresent disclosure.

FIGS. 9A and 9B are a top perspective views of one example embodiment ofthe anchor system of the present disclosure.

FIG. 9C is a partially exploded top perspective view of the anchorsystem of FIGS. 9A and 9B.

FIGS. 9D and 9E are partially exploded top perspective views of theanchor system of FIGS. 9A and 9B with some components removed.

FIG. 9F is a partially exploded top perspective view of the drumassembly and the level wind system of the anchor system of FIGS. 9A and9B.

FIG. 9G is a cross-sectional top perspective view of the anchor systemof FIGS. 9A and 9B taken substantially along line 9G-9G of FIG. 9A.

FIG. 9H is a top perspective view of the anchor system of FIGS. 9A and9B stored in a storage container with other accessories.

FIG. 10A is a schematic block diagram of a hydraulic system of theanchor system of FIGS. 9A and 9B during a flexible capture memberhaul-in phase of the fixed-wing aircraft retrieval process.

FIG. 10B is a schematic block diagram of the hydraulic system of FIG.10A during a neutral phase of the fixed-wing aircraft retrieval processwhile the accumulator is charging.

FIG. 10C is a schematic block diagram of the hydraulic system of FIG.10A during a neutral phase of the fixed-wing aircraft retrieval processafter the accumulator has been charged and the pump is powered off.

FIG. 10D is a schematic block diagram of the hydraulic system of FIG.10A during a flexible capture member payout phase of the fixed-wingaircraft retrieval process.

FIG. 11A is a top perspective view of an aircraft-landing structure ofthe present disclosure.

FIG. 11B is a front elevational view of the aircraft-landing structureof FIG. 11A.

FIG. 11C is a top plan view of the aircraft-landing structure of FIG.11A.

FIG. 11D is a bottom plan view of the aircraft-landing structure of FIG.11A.

FIG. 11E is a cross-sectional side elevational view of theaircraft-landing structure of FIG. 11A taken substantially along line11E-11E of FIG. 11C.

FIG. 11F is a cross-sectional side elevational view of an upper portionof the aircraft-landing structure of FIG. 11A taken substantially alongline 11E-11E of FIG. 11C.

FIG. 11G is a cross-sectional side elevational view of an intermediateportion of the aircraft-landing structure of FIG. 11A takensubstantially along line 11E-11E of FIG. 11C.

FIG. 11H is a top perspective view of an upper guiding sealing componentof the aircraft-landing structure of FIG. 11A.

FIG. 11I is a cross-sectional side elevational view of the upper guidingcomponent of FIG. 11H taken substantially along line 11I-11I of FIG.11H.

FIG. 11J is a top perspective view of the intermediate guiding componentof the aircraft-landing structure of FIG. 11A.

FIG. 11K is a cross-sectional side elevational view of the intermediateguiding component of FIG. 11J taken substantially along line 11K-11K ofFIG. 11J.

FIG. 11L is a top perspective view of the lower guiding and mountingcomponent of the aircraft-landing structure of FIG. 11A.

FIG. 11M is a cross-sectional side elevational view of the lower guidingand mounting component of FIG. 11L taken substantially along line11M-11M of FIG. 11L.

FIG. 12A is a partial cross-sectional view of the saddle of FIG. 4Ashowing the cam in an attached rotational position and a hook of thefixed-wing aircraft attached taken substantially along line 10A-10A ofFIG. 4C.

FIG. 12B is a partial cross-sectional view of the saddle of FIG. 4Ashowing the cam halfway between the attached rotational position and therelease rotational position and the hook of the fixed-wing aircraftbeing pushed off of the cam taken substantially along line 10A-10A ofFIG. 4C.

FIG. 12C is a partial cross-sectional view of the saddle of FIG. 4Ashowing the cam in the release rotational position and the hook of thefixed-wing aircraft released from the cam taken substantially along line10A-10A of FIG. 4C.

FIG. 12D is a diagrammatic view of the multicopter of FIG. 1A, thefixed-wing aircraft of FIG. 1A, a flexible capture member, theaircraft-landing structure of FIG. 11A, and the anchor system of FIGS.9A and 9B just before the fixed-wing aircraft captures the flexiblecapture member.

FIG. 12E is a diagrammatic view of the multicopter, the fixed-wingaircraft, the flexible capture member, the aircraft-landing structure,and the anchor system just after the fixed-wing aircraft captures theflexible capture member and as the anchor system is paying out flexiblecapture member.

FIG. 12F is a diagrammatic view of the multicopter, the fixed-wingaircraft, the flexible capture member, the aircraft-landing structure,and the anchor system after the fixed-wing aircraft has stopped movingand the anchor system has retracted the paid-out portion of the flexiblecapture member.

FIG. 12G is a diagrammatic view of the multicopter, the fixed-wingaircraft, the flexible capture member, the aircraft-landing structure,and the anchor system after the multicopter has lowered the fixed-wingaircraft onto the aircraft-landing structure.

FIG. 12H is a graph of two pressures during the fixed-wing aircraftretrieval process employing the anchor system with the hydraulic systemof FIGS. 10A-10D.

FIG. 13A is a schematic block diagram of an alternative hydraulic systemof an alternative anchor system during a flexible capture member haul-inphase of the fixed-wing aircraft retrieval process.

FIG. 13B is a schematic block diagram of the hydraulic system of FIG.13A during a neutral phase of the fixed-wing aircraft retrieval processwhile the accumulator is charging.

FIG. 13C is a schematic block diagram of the hydraulic system of FIG.13A during a neutral phase of the fixed-wing aircraft retrieval processafter the accumulator has been charged and the pump is powered off.

FIG. 13D is a schematic block diagram of the hydraulic system of FIG.13A during a flexible capture member payout phase of the fixed-wingaircraft retrieval process.

FIG. 13E is a graph of two pressures during the fixed-wing aircraftretrieval process employing the hydraulic system of FIGS. 13A-13D.

FIG. 14A is a top perspective view of an alternative fixed-wing aircraftattached to an alternative saddle.

FIG. 14B is a top perspective view of the saddle of FIG. 14A.

FIG. 14C is a cross-sectional view of the saddle of FIG. 14A takensubstantially along line 14C-14C of FIG. 14B and with certain elementsremoved.

FIGS. 14D and 14E are, respectively, assembled and exploded topperspective views of a rear engager of the saddle of FIG. 14A.

FIG. 14F is an exploded top perspective view of the attachment/releasedevice of the part of the saddle of FIG. 14A.

FIGS. 14G-14I are cross-sectional side elevational views of the part ofthe saddle of FIG. 14A showing different configurations of the lock armand the front engager arm.

DETAILED DESCRIPTION

While the features, methods, devices, and systems described herein maybe embodied in various forms, there are shown in the drawings, and willhereinafter be described, some exemplary and non-limiting embodiments.Not all of the depicted components described in this disclosure may berequired, however, and some implementations may include additional,different, or fewer components from those expressly described in thisdisclosure. Variations in the arrangement and type of the components;the shapes, sizes, and materials of the components; and the manners ofattachment and connections of the components may be made withoutdeparting from the spirit or scope of the claims as set forth herein.This specification is intended to be taken as a whole and interpreted inaccordance with the principles of the invention as taught herein andunderstood by one of ordinary skill in the art.

The rotorcraft-assisted fixed-wing aircraft launch and retrieval system(sometimes called the “launch and retrieval system” for brevity) ofvarious embodiments of the present disclosure is usable to launch afixed-wing aircraft 20 a into free, wing-borne flight and to retrievethe fixed-wing aircraft 20 a from free, wing-borne flight. While thefixed-wing aircraft 20 a may be any suitable fixed-wing aircraft, thefixed-wing aircraft of the example embodiments described below include:(1) the SCANEAGLE unmanned aerial vehicle 20 a (SCANEAGLE is aregistered trademark of the Boeing Company); and (2) the INTEGRATORunmanned aerial vehicle 20 b (INTEGRATOR is a registered trademark ofInsitu, Inc.).

The launch and retrieval system includes a modular multicopter 10, astorage and launch system 2000, an anchor system 3000, a flexiblecapture member 5000, and an aircraft-landing structure 8000. Themulticopter 10 is attachable to the fixed-wing aircraft 20 a tofacilitate launching the fixed-wing aircraft 20 a into free, wing-borneflight. The storage and launch system 2000 is usable to store themulticopter 10 (when disassembled) and to act as a launch mount for thefixed-wing aircraft 20 a by retaining the fixed-wing aircraft 20 a in adesired launch orientation. The anchor system 3000 is usable with themulticopter 10, the flexible capture member 5000, and theaircraft-landing structure 8000 to retrieve the fixed-wing aircraft 20 afrom free, wing-borne flight.

Generally, to launch the fixed-wing aircraft 20 a into free, wing-borneflight, an operator (or operators): (1) removes the disassembledmulticopter 10 from a container of the storage and launch system 2000;(2) assembles the multicopter 10; (3) mounts the fixed-wing aircraft 20a to a launch-assist assembly of the storage and launch system 2000,which retains the fixed-wing aircraft 20 a in a desired launchorientation; (4) attaches the multicopter 10 to the fixed-wing aircraft20 a; (5) controls the multicopter 10 to lift the fixed-wing aircraft 20a to a desired altitude and to accelerate to a desired speed; (6)controls the multicopter 10 to release the fixed-wing aircraft 20 a intofree, wing-borne flight; and (7) controls the multicopter 10 to land.

Generally, to retrieve the fixed-wing aircraft 20 a from free,wing-borne flight, an operator (or operators): (1) attaches a free endof the flexible capture member 5000 to the multicopter 10 such that theflexible capture member 5000 extends from a drum of the anchor system3000 through the aircraft-landing structure 8000 to the multicopter 10;(2) inflates the aircraft-landing structure 8000 such that it ispositioned above the anchor system 3000; (3) controls the multicopter 10to fly to a designated altitude above the anchor system 3000 and tostation-keep relative to the anchor system 3000 such that the flexiblecapture member 5000 extends therebetween and the anchor system 3000regulates the tension in the flexible capture member 5000; (4) controlsthe fixed-wing aircraft 20 a to contact and capture the flexible capturemember 5000; (5) controls the multicopter 10 to descend such that thefixed-wing aircraft 20 a contacts the aircraft-landing structure 8000and a ground crew can secure the fixed-wing aircraft 20 a; and (6)controls the multicopter 10 to land.

While the multicopter 10 includes eight rotors in the exampleembodiments described below, the launch and retrieval system may includeany suitable rotorcraft including any suitable quantity of rotors, suchas one rotor, two rotors, or four rotors.

1. Multicopter

FIGS. 1A, 1B, 1C, 1D, 1E, 1F, and 1G show the multicopter 10. Themulticopter 10 is modular in that it is assembled from (and can bedisassembled into) a plurality of different modules or subassemblies.The multicopter is removably attachable to: (1) the fixed-wing aircraft20 a to facilitate launch of the fixed-wing aircraft 20 a into free,wing-borne flight, and (2) to the flexible capture member 5000 tofacilitate retrieval of the fixed-wing aircraft 20 a from free,wing-borne flight.

As best shown in FIGS. 1E and 1F, the multicopter 10 includes thefollowing 13 modules or subassemblies: a hub module 100; first, second,third, and fourth rotor arm modules 400 a, 400 b, 400 c, and 400 d;first and second front landing gear extension modules 500 a and 500 b;first and second rear landing gear extension modules 500 c and 500 d;first and second front landing gear modules 600 a and 600 b; and firstand second rear landing gear modules 600 c and 600 d.

As described in detail below, to assemble the multicopter 10 from these13 modules or subassemblies, after removing the 13 modules from thecontainer of the storage and launch system 2000, an operator: (1)attaches the first, second, third, and fourth rotor arm modules 400 a,400 b, 400 c, and 400 d to the hub module 100; (2) attaches the firstand second front landing gear extension modules 500 a and 500 b to thefirst and second rotor arm modules 400 a and 400 b, respectively; (3)attaches the first and second rear landing gear extension modules 500 cand 500 d to the third and fourth rotor arm modules 400 c and 400 d,respectively; (4) attaches the first and second front landing gearmodule 600 a and 600 b to the first and second front landing gearextension modules 500 a and 500 b, respectively; and (5) attaches thefirst and second rear landing gear module 600 c and 600 d to the firstand second rear landing gear extension modules 500 c and 500 d,respectively.

The modularity of this multicopter is beneficial compared to non-modularor unitary multicopter construction. First, the modularity of thismulticopter enables an operator to quickly and easily disassemble thisrelatively large multicopter into 13 smaller modules or subassemblies.The operator can compactly store these modules or subassemblies into asingle container, which makes the disassembled multicopter easy to storeand transport compared to the assembled multicopter. Second, if a partof this multicopter breaks, its modularity enables the operator toquickly and easily replace the module(s) or subassembly(ies) includingthe broken part with a properly functioning replacement module(s) orsubassembly(ies) rather than waste time repairing the brokencomponent(s).

FIG. 1G is a block diagram of certain electrically controlled componentsof the multicopter 10. In this embodiment, although not shown in FIG.1G, four (or any suitable quantity of) lithium-ion batteries (or anyother suitable power source(s)) power these components (as describedbelow). For a given component, the power source may be directlyelectrically connected to that component to power that component orindirectly electrically connected to that component (e.g., via anothercomponent) to power that component.

The hub module 100 includes a hub base 200 and a saddle 300. The hubbase 200 includes: (1) a controller 272; (2) a communications interface274; (3) an inertial measurement unit (IMU) 277; (4) a barometer 278 (orother suitable pressure sensor); (5) a GPS receiver 285; and (6) eightelectronic speed controllers (ESCs) 265 a, 265 b, 265 c, 265 d, 265 e,265 f, 265 g, and 265 h. The saddle 300 includes: (1) a cam servo motor381; and (2) a lock servo motor 391. This is merely one exampleconfiguration, and these components may be located on any suitable partof the multicopter in other embodiments. The first rotor arm module 400a includes an upper rotor motor 465 a and a lower rotor motor 465 b. Thesecond rotor arm module 400 b includes an upper rotor motor 465 c and alower rotor motor 465 d. The third rotor arm module 400 c includes anupper rotor motor 465 e and a lower rotor motor 465 f. The fourth rotorarm module 400 d includes an upper rotor motor 465 g and a lower rotormotor 465 h.

The controller 272 is electrically and communicatively connected to thecommunications interface 274, the IMU 277, the barometer 278, the GPSreceiver 285, the ESCs 265 a to 265 h, the cam servo motor 381, and thelock servo motor 391.

The controller 272 includes a processor 272 a and a memory 272 b. Theprocessor 272 a is configured to execute program code or instructionsstored in the memory 272 b to control operation of the multicopter 10,as described herein. The processor 272 a may be one or more of: (1) ageneral-purpose processor; (2) a content-addressable memory; (3) adigital-signal processor; (4) an application-specific integratedcircuit; (5) a field-programmable gate array; (6) any suitableprogrammable logic device, discrete gate, or transistor logic; (7)discrete hardware components; and (8) any other suitable processingdevice.

The memory 272 b is configured to store, maintain, and provide data asneeded to support the functionality of the multicopter 10. For instance,in various embodiments, the memory 272 b stores program code orinstructions executable by the processor 272 a to control themulticopter 10. The memory 272 b may be any suitable data storagedevice, such as one or more of: (1) volatile memory (e.g., RAM, whichcan include non-volatile RAM, magnetic RAM, ferroelectric RAM, and anyother suitable forms); (2) non-volatile memory (e.g., disk memory, FLASHmemory, EPROMs, EEPROMs, memristor-based non-volatile solid-statememory, etc.); (3) unalterable memory (e.g., EPROMs); and (4) read-onlymemory.

The communications interface 274 is a suitable wireless communicationinterface, such as a transceiver like an MM2 900 MHz Embedded Radio byFreewave Technologies, configured to establish and facilitatecommunication between the controller 272 and: (1) a computing device(such as a laptop computer, a tablet computer, or a mobile phone, notshown); and (2) an R/C controller (not shown) that the operator of themulticopter 10 controls. In operation, once the communications interface274 establishes communication with the computing device, the controller272 can send data (via the communications interface 274) associated withthe operation of the multicopter 10 (such as the operational status ofthe multicopter 10, GPS coordinates of the multicopter 10, rotor motorstatus, IMU or other sensor measurements, altitude, GPS receptionhealth, magnetometer health, attitude, and the like) to the computingdevice. Once the communications interface 274 establishes communicationwith the R/C controller, the controller 272 can receive signals (via thecommunications interface 274) from the R/C controller. Morespecifically, upon receipt of these signals from the R/C controller, thecommunications interface 274 converts these signals into a formatreadable by the controller 272 and sends the converted signals to thecontroller 272 for processing.

The above-described communication may be bidirectional orunidirectional. In some embodiments, the communications interface 274enables the controller 272 to send data to the computing device but notreceive data from the computing device. In other embodiments, thecommunications interface 274 enables the controller 272 to send data tothe computing device and to receive data from the computing device. Insome embodiments, the communications interface 274 enables thecontroller 272 to receive signals from the R/C controller but not sendsignals to the R/C controller. In other embodiments, the communicationsinterface 274 enables the controller 272 to receive signals from the R/Ccontroller and send signals to the R/C controller.

In certain embodiments, the communications interface 274 includesseparate components for communicating with the computing device (such asa telemetry link) and the R/C controller (such as an R/C receiver).

The IMU 277 includes: (1) multiple accelerometers 277 a configured tosense the linear acceleration of the multicopter 10 with respect tothree orthogonal reference axes (e.g., standard orthogonal x-, y, andz-axes); (2) multiple gyroscopes 277 b configured to sense the angularrotation of the multicopter 10 with respect to the pitch, yaw, and rollaxes of the multicopter 10; and (3) a magnetometer 277 c configured toenable the controller 272 to determine the heading of the multicopter 10(i.e., the direction in which the multicopter 10 is pointed relative toEarth). More specifically, the magnetometer 277 c is configured to sensethe Earth's magnetic field and transmit a signal representing thedirection of the Earth's magnetic North to the controller 272. Thecontroller 272 is configured to use the GPS coordinates of themulticopter 10 and a global map of declination angle (the angle betweenthe Earth's true North and the Earth's magnetic North) to determine arequired correction angle. The controller 272 is configured to apply therequired correction angle to the direction of the Earth's magnetic Northto obtain the direction of the Earth's true North. The controller 272 isconfigured to use this information to determine the heading of themulticopter 10. In other embodiments, a pair of GPS receivers are usedinstead of the magnetometer to maintain more accurate heading. Thispractice is especially useful when the multicopter is operating in closeproximity to large iron objects—such as ship hulls—or when thedifference between the Earth's magnetic North and true North is large,such as near the Earth's poles.

The accelerometers 277 a, the gyroscopes 277 b, and the magnetometer 277c continuously or periodically obtain these sensor readings andcontinuously or periodically transmit corresponding signals to thecontroller 272, which uses these sensor readings in a variety ofdifferent ways described herein. This is merely one example IMU, and theIMU may include any suitable sensors.

The barometer 278 is configured to sense the atmospheric pressure and totransmit a signal representing the sensed atmospheric pressure to thecontroller 272. The controller 272 is configured to use the sensedatmospheric pressure to determine: (1) the height of the multicopter 10above sea level; and (2) the height of the multicopter 10 above theground or any other suitable reference location. For instance, todetermine the height of the multicopter 10 above the ground, thecontroller 272 uses a reference atmospheric pressure sensed by thebarometer 278 while the multicopter 10 is on the ground just beforetakeoff to determine the height of the ground above sea level. Once themulticopter 10 is airborne, at any given point in time the controller272 is configured to determine the height of the multicopter 10 abovethe ground by: (1) using the atmospheric pressure sensed by thebarometer 278 to determine the height of the multicopter 10 above sealevel; and (2) determining the difference between the height of themulticopter 10 above sea level and the height of the ground above sealevel. This is merely one example way of determining the height of themulticopter above a reference point. Any other suitable method may beemployed.

The GPS receiver 285 is communicatively connectable with (such as via asuitable wireless protocol) GPS satellites (not shown), as is known inthe art. The GPS receiver 285 is configured to receive signals from oneor more of the GPS satellites, to determine the multicopter's locationusing those signals, and to transmit signals representing themulticopter's location to the controller 272.

The ESC 265 a is electrically connected to and, along with thecontroller 272, controls the operation of the upper rotor motor 465 a ofthe first rotor arm module 400 a. The ESC 265 b is electricallyconnected to and, along with the controller 272, controls the operationof the lower rotor motor 465 b of the first rotor arm module 400 a. TheESC 265 c is electrically connected to and, along with the controller272, controls the operation of the upper rotor motor 465 c of the secondrotor arm module 400 b. The ESC 265 d is electrically connected to and,along with the controller 272, controls the operation of the lower rotormotor 465 d of the second rotor arm module 400 b. The ESC 265 e iselectrically connected to and, along with the controller 272, controlsthe operation of the upper rotor motor 465 e of the third rotor armmodule 400 c. The ESC 265 f is electrically connected to and, along withthe controller 272, controls the operation of the lower rotor motor 465f of the third rotor arm module 400 c. The ESC 265 g is electricallyconnected to and, along with the controller 272, controls the operationof the upper rotor motor 465 g of the fourth rotor arm module 400 d. TheESC 265 h is electrically connected to and, along with the controller272, controls the operation of the lower rotor motor 465 h of the fourthrotor arm module 400 d.

The controller 272 is configured to send rotor motor control signals tothe ESCs 265 a to 265 h to control operation of the rotor motors 465 ato 465 h in accordance with received control signals and/or controlsignals the controller 272 generates via any of the software subroutinesdisclosed herein.

1.1 Hub Module

FIGS. 2A, 2B, and 2C show the hub module 100. The hub module 100: (1)serves as the attachment point for the rotor arm modules 400 a to 400 d;(2) is the portion of the multicopter 10 to which the fixed-wingaircraft 20 a is attached for launch; (3) is the portion of themulticopter 10 to which the flexible capture member 5000 is attached forretrieval of the fixed-wing aircraft 20 a; (4) includes the power sourcefor the multicopter 10; and (5) includes certain components used tocontrol operation of the multicopter 10.

As best shown in FIG. 2C, the hub module 100 includes a hub base 200 anda saddle 300. The saddle 300 is attached to the underside of the hubbase 200 via two brackets 120 a and 120 b and four struts 110 a, 110 b,110 c, and 110 d. Each strut 110 is attached at one end to the hub base200 and at the other end to the saddle 300. This is merely one exampleof how the saddle can be attached to the hub base, and in otherembodiments the saddle may be attached to the hub base in any suitablemanner. For instance, in another embodiment, rather than being attachedto the hub base, each strut is attached to a different rotor arm module,such as to one of the rotor motor assemblies of the rotor arm modules.

1.1.1 Hub Base

FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, and 3H show the hub base 200 orcomponents thereof. The hub base 200 is the portion of the hub module100 that: (1) serves as the attachment point for the rotor arm modules400 a to 400 d; (2) includes the power source for the multicopter 10;and (3) includes certain components used to control operation of themulticopter 10.

As best shown in FIGS. 3C and 3D, the hub base 200 includes two hollowelongated rectangular supports 210 a and 210 b. The hollow supports 210a and 210 b interlock with one another near their centers such that thehollow supports 210 a and 210 b are oriented transversely (such asgenerally perpendicularly) to one another and generally form a crossshape when viewed from above or below. Reinforcing plugs 212 aredisposed within the hollow supports 210 a and 210 b such that fastenerreceiving openings (not labeled) of the reinforcing plugs 212 verticallyalign with fastener receiving openings (not labeled) of the hollowsupports 210 a and 210 b. Upper and lower braces 220 a and 220 bsandwich the hollow supports 210 a and 210 b. A fastener 222 threadedthrough the upper brace 220 a, the hollow support 210 a, the reinforcingplug 212, the hollow support 210 b, and the lower brace 220 b holds theupper and lower braces 220 a and 220 b and the hollow supports 210 a and210 b together. This ensures the hollow supports 210 a and 210 b remaininterlocked and ensures their orientation with respect to one anotherdoes not substantially change.

The hollow supports 210 a and 210 b are attached to a hub base plate 202via suitable fasteners (not labeled) threaded through the hollowsupports 210 a and 210 b and the reinforcing plugs 212 disposed withinthe hollow supports 210 a and 210 b. As best shown in FIG. 2B, twostabilizers 290 a and 290 b are attached to and extend downward fromeither hollow support 210 a and 210 b. The free ends of the stabilizers290 a and 290 b terminate in feet configured to contact the fixed-wingaircraft 20 a to help prevent the fixed-wing aircraft 20 a from rotatingaround its roll axis relative to the multicopter 10. The feet areadjustable in length (e.g., are threaded such that they can be shortenedby threading further into the stabilizers or lengthened by unthreadingfurther out of the stabilizers).

As best shown in FIG. 3C, first and third isolator plate mounts 240 aand 240 c are attached (such as via lashing) to the hollow support 210 aand second and fourth isolator plate mounts 240 b and 240 d are attached(such as via lashing) to the hollow support 210 b radially inward of theends of the hollow supports 210 a and 210 b. Each isolator plate mount240 includes a first isolator plate mounting post 242 defining athreaded fastener receiving opening at least partially therethrough anda second isolator plate mounting post 244 defining a threaded fastenerreceiving opening at least partially therethrough.

An isolator plate 250 is slidably mounted to the isolator plate mounts240 a, 240 b, 240 c, and 240 d. FIGS. 3E and 3F show how the isolatorplate 250 is mounted to the isolator plate mount 240 b. For simplicityand brevity, illustrations of how the isolator plate 250 is mounted tothe remaining three isolator plate mounts 240 a, 240 c, and 240 d in asimilar manner are not provided.

The isolator plate 250 defines first and second mounting openings 250 aand 250 b therethrough. An elastomeric grommet 252 is installed in thefirst mounting opening 250 a of the isolator plate 250. The grommet 252defines a first isolator plate mounting post receiving channel 252 atherethrough, and the first isolator plate mounting post 242 b isslidably received in the first isolator plate mounting post receivingchannel 252 a. A fastener 254 having a stop washer 254 a beneath itshead is partially threaded into the fastener receiving opening of thefirst isolator plate mounting post 242 b. Upper and lower conicalsprings 256 a and 256 b—held in place by a fastener 258 partiallythreaded into the fastener receiving opening of the second isolatorplate mounting post 244 b—sandwich the isolator plate 250.

The hollow support 210 b and the stop washer 254 a constrain thevertical movement of the isolator plate 250. In other words, theisolator plate 250 can move vertically between a lower position in whichthe grommet 252 contacts the hollow support 210 b and an upper positionin which the grommet 252 contacts the stop washer 254 a. The conicalsprings 256 a and 256 b act as a suspension that absorbs (or partiallyabsorbs) vibrations of the hollow support 210 b that would otherwise bedirectly transferred to the isolator plate 250, which could affectoperation of certain components of the multicopter 10 (such as thecontroller 272).

The relatively high mass of the batteries 260 a to 260 d and the factthat they are mounted to the isolator plate 250 and close-coupled to theIMU 277 works with the suspension to help prevent undesired vibration ofthe isolator plate 250 and therefore the IMU 277. In certainembodiments, for the IMU 277 to perform well, the IMU 277 must resolveaccelerations on the order of 0.1 gee and rotations of 0.1radians/second. The IMU 277 cannot do this reliably when (˜10-gee)vibration, caused by rotor unbalance, for example, is transmitted fromthe airframe of the multicopter 10 to the IMU 277. When the mass of thebatteries 260 a to 260 d is used to ballast the IMU 277 on the isolatorplate 250, and the isolator plate 250 is anchored to the airframestructure through the suspension, the IMU 277 enjoys the vibration-freemounting location. By mounting the isolator plate 250 well-outboard atits corners, the IMU 277 remains sufficiently well-coupled to theairframe that pitch and roll movements are transmitted to the IMU 277,which is able to effectively resolve these motions.

As best shown in FIGS. 3A and 3B, The following components are mountedto the isolator plate 250: (1) the batteries 260 a, 260 b, 260 c, and260 d; (2) the ESCs 265 a to 265 h; (3) an avionics enclosure 270 thathouses a variety of components including the controller 272 and thecommunications interface 274; (4) a GPS antenna mounting bracket 280 onwhich the GPS antenna 285 is mounted; (5) navigation lights (not shown);and (6) a Mode C transponder (not shown).

The four open ends of the hollow supports 210 a and 210 b form rotor armmodule receiving sockets that can receive one of the rotor arm modules400 a to 400 d. Specifically, the hollow support 210 a forms a firstrotor arm module receiving socket 214 a and a third rotor arm modulereceiving socket (not shown) and the hollow support 210 b forms a secondrotor arm module receiving socket 214 b and a fourth rotor arm modulereceiving socket (not shown).

As best shown in FIG. 3A, female blind mate assemblies are attached tothe ends of the hollow supports 210 a and 210 b. Specifically, a firstfemale blind mate assembly 230 a is attached to one end of the hollowsupport 210 a near the first rotor arm module receiving socket 214 a, asecond female blind mate assembly 230 b is attached to one end of thehollow support 210 b near the second rotor arm module receiving socket214 b, a third female blind mate assembly 230 c is attached to the otherend of the hollow support 210 a near the third rotor arm modulereceiving socket 214 c, and a fourth female blind mate assembly 230 d isattached to the other end of the hollow support 210 b near the fourthrotor arm module receiving socket 214 d.

The female blind mate assemblies 230 (along with the corresponding maleblind mate connectors described below with respect to the rotor armmodules) facilitate: (1) mechanical attachment of the rotor arm modules400 a, 400 b, 400 c, and 400 d to the hub module 100; (2) power flowfrom the battery(ies) 260 a, 260 b, 260 c, and/or 260 d to the rotormotors 465 a to 465 h of the rotor arm modules 400 a, 400 b, 400 c, and400 d; and (3) communication between the ESCs 265 a to 265 h and therotor motors 465 a to 465 h.

FIGS. 3G and 3H show the second female blind mate assembly 230 b. Thefemale blind mate assemblies 230 a, 230 c, and 230 d are similar to thesecond female blind mate assembly 230 b and are therefore not separatelyshown or described.

The second female blind mate assembly 230 b includes: (1) a female blindmate connector 231 b including a plurality of pin receptacles (notlabeled); (2) three elastomeric grommets 232 b; (3) three rigid, hollowcylindrical spacers 233 b; (4) three fasteners 234 b; (5) three nuts 235b; (6) a mounting bracket 236 b; and (7) mounting bracket fasteners (notlabeled).

Although not shown for clarity, the female blind mate connector 231 band, particularly, the pin receptacles, are electrically connected tothe corresponding ESCs 265 c and 265 d via wiring. In this exampleembodiment, the female blind mate connector 231 b includes 12 pinreceptacles, six of which are connected to the ESC 265 c via wiring andthe other six of which are connected to the ESC 265 d via wiring.

The mounting bracket 236 b is positioned at a desired location along thehollow support 210 b, and the mounting bracket fasteners are tightenedto clamp the mounting bracket 236 b in place relative to the hollowsupport 210 b.

The female blind mate connector 231 b is flexurally mounted to themounting bracket 236 b via the elastomeric grommets 232 b, the spacers233 b, the fasteners 234 b, and the nuts 235 b. Specifically, theelastomeric grommets 232 b are fitted into corresponding cavities in thefemale blind mate connector 231 b. As best shown in FIG. 3H, each cavityincludes an inwardly projecting annular rib that fits into acorresponding annular cutout of the corresponding elastomeric grommet232 b. The spacers 233 b are disposed within longitudinal bores definedthrough the elastomeric grommets 232 b. The fasteners 234 b extendthrough the hollow spacers 233 b and through corresponding fastenerreceiving openings defined through the mounting bracket 236 b into theircorresponding nuts 235 b. This secures the female blind mate connector231 b to the mounting bracket 236 b.

This flexural mount of the female blind mate connector to the mountingbracket via the elastomeric grommets is beneficial compared to a rigidconnection of the female blind mate connector to the mounting bracket.The flexural mount enables the female blind mate connector to move—viadeformation of the elastomeric grommet—relative to the mounting bracket(and the rest of the hub module) when loads are applied to the femaleblind mate connector, such as loads imposed on the female blind mateconnector by the attached rotor arm module during flight. Because thefemale blind mate connector is not rigidly attached to the correspondingmounting bracket, it is less likely that the pins of the male blind mateconnector (described below) received by the pin receptacles of thefemale blind mate connector will lose electrical contact—causing themulticopter 10 to lose control of at least one of its rotor motors—whenloads are applied to the female blind mate connector.

As best shown in FIG. 3H, a latch plate 237 is attached to the undersideof each hollow support 210 a and 210 b below each female blind mateconnector 231 attached thereto. The latch plate 237 includes a clawengager 238 and a backstop 239. The latch plate 237 is described belowwith respect to the locking assemblies 420 of the rotor arm modules 400a to 400 d.

In some embodiments, the hub module (either the hub base, the saddle, orboth) or other elements of the multicopter include ballast to obtain adesired weight distribution and/or provide stability during flight.

1.1.2 Saddle

FIGS. 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, 4I, and 4J show the saddle 300 orcomponents thereof. The saddle 300 is the portion of the hub module 100:(1) to which the fixed-wing aircraft 20 a is attached for launch; (2)from which the fixed-wing aircraft 20 a is released for launch; and (3)to which the flexible capture member 5000 is attached for retrieval ofthe fixed-wing aircraft 20 a. The saddle 300 also enables the operatorto vary the pitch angle of the fixed-wing aircraft 20 a relative to themulticopter 10.

As best shown in FIG. 4C, the saddle 300 includes a saddle base bracket310 and first and second saddle side plates 320 a and 320 b. The firstand second saddle side plates 320 a and 320 b are pivotably connected toopposite sides of the saddle base bracket 310 near the front end of thesaddle base bracket 310. The first and second saddle side plates 320 aand 320 b are also attached to opposite sides of the saddle base bracket310 near the rear end of the saddle base bracket 310 via locking devices322 a and 322 b (which are cam lever locks in this example embodimentbut can be any suitable locking devices). The locking devices 322 a and322 b extend through respective slots 321 a and 322 b defined throughthe respective first and second side plates 320 a and 320 b.

As shown in FIGS. 4D and 4E, the orientation of the slots 321 a and 321b enables an operator to vary the angle α formed between a planeincluding the tops of the first and second saddle side plates 320 a and320 b—to which the hub base 200 is attached—and a plane including thegenerally horizontally extending bottom portion of the saddle base plate310. The angle α generally corresponds to the angle formed between thehub base plate 202 of the hub base 200 and the fuselage of thefixed-wing aircraft 20 a when the fixed-wing aircraft 20 a is attachedto the saddle 300. To change the angle α, the operator unlocks thelocking devices 322 a and 322 b, rotates the first and second sideplates 320 a and 320 b relative to the saddle base bracket 310 aroundtheir pivotable attachments to the saddle base bracket 310 to thedesired rotational position (or vice-versa), and re-locks the lockingdevices 322 a and 322 b. In this example embodiment, the angle α isvariable from about 0 degrees to about 10 degrees, though in otherembodiments the angle α is variable between any suitable angles.

In certain embodiments, an operator can cause the first and second sideplates to rotate relative to the saddle while the multicopter 10 isflying. For instance, the operator may desire to release the fixed-wingaircraft nose-down from a hover. Conversely, the operator may desire torelease the fixed-wing aircraft nose-up (such as nose-up about 10degrees) to facilitate launch while the multicopter is dashing forward(this nose-up pitch reduces wind drag and better aligns the thrustvector of the fixed-wing aircraft with the desired direction of travel).The multicopter may include any suitable combination of elements tofacilitate this remote pivoting, such as various motors, actuators, andthe like.

As best shown in FIGS. 4A, 4B, and 4C, a stabilizing bracket 330 isattached to the first and second saddle side plates 320 a and 320 b andextends across the space between the first and second saddle side plates320 a and 320 b. A downwardly curved front aircraft engaging bracket 340a is attached to the underside of the saddle base bracket 310 near thefront of the saddle base bracket 310. A downwardly curved rear aircraftengaging bracket 340 b is attached to the underside of the saddle basebracket 310 near the rear of the saddle base bracket 310.

As best shown in FIG. 4C, a cam 350 is rotatably attached to and extendsacross the width of the saddle base bracket 310 such that the cam 350 istransverse (such as generally perpendicular) to the first and secondsaddle side plates 320 a and 320 b. As best shown in FIGS. 4F, 4H, and4I, the portion of the cam 350 near its longitudinal center has anirregularly shaped profile including a first relatively wide ridge 351,a second relatively narrow ridge 353, and a valley 352 between the firstand second ridges 351 and 353. This irregularly shaped profilefacilitates attaching the fixed-wing aircraft 20 a to the cam 350 (andtherefore to the multicopter 10) and releasing the fixed-wing aircraft20 a from the cam 350 (and therefore from the multicopter 10), asdescribed below with respect to FIGS. 12A, 12B, and 12C. The cam 350also includes a cam control arm 354 and a foot 355 extendingtransversely (such as generally perpendicularly) from the longitudinalaxis of the cam 350.

An aircraft attaching/releasing assembly 380 attached to the saddle basebracket 310 controls rotation of the cam 350 relative to the saddle basebracket 310. As best shown in FIG. 4G, the aircraft attaching/releasingassembly 380 includes: (1) a cam servo motor 381 having a cam servomotor shaft 381 a; (2) a cam servo motor arm 382; (3) a cam servo motorarm lock device 382 a; (4) upper and lower servo spacers 383 a and 383b; (5) upper and lower nut plates 384 a and 384 b; (6) fasteners 385;(7) a cam rotation control link 386 having connectors 386 a and 386 b ateither end; (8) a lock servo motor 391 having a lock servo motor shaft391 a; and (9) a lock servo arm 392 terminating at one end in a lockservo motor locking extension 392 a.

The cam servo motor 381 and the lock servo motor 391 are attached to oneanother and to the saddle base bracket 310 via the fasteners 385, theupper and lower servo spacers 383 a and 383 b, and the upper and lowernut plates 384 a and 384 b. The cam servo motor arm 382 is attached nearone end to the cam servo motor shaft 381 a and near the other end to theconnector 386 a. The connector 386 b is attached to the cam control arm354 of the cam 350, which links the cam servo motor shaft 381 a to thecam 350. The cam servo motor arm lock device 382 a is attached to thecam servo motor arm 382 between the connector 386 a and the cam servomotor shaft 381 a. The lock servo arm 392 is attached to the lock servomotor shaft 391 a. The rearwardly extending portion of the lock servoarm 392 terminates in the lock servo motor locking extension 392 a,which is engageable to the cam servo motor arm lock device 382 a incertain instances.

The cam servo motor 381 controls rotation of the cam 350 relative to thesaddle base bracket 310. To rotate the cam 350, the cam servo motor 381rotates the cam servo motor shaft 381 a, which rotates the attached camservo arm 382, which in turn rotates the cam 350 via the cam rotationcontrol link 386. The cam servo motor 381 can rotate the cam 350 from anattached rotational position—shown in FIG. 4H—to a release rotationalposition—shown in FIG. 4I (and vice-versa).

The lock servo motor 391 controls rotation of the lock servo arm 392between a cam rotation-preventing rotational position—shown in FIG.4H—and a cam rotation-enabling rotational position—shown in FIG. 4I (andvice-versa). When the cam 350 is in the attached rotational position andthe lock servo arm 392 is in the cam rotation-preventing rotationalposition, the lock servo motor locking extension 392 a engages the camservo motor arm lock device 382 a of the cam servo motor arm 382. Thisprevents the cam servo motor 381 from rotating the cam 350 from theattached rotational position to the release rotational position.

FIGS. 4H and 4I show how the cam servo motor 381 and the lock servomotor 391 operate to rotate the cam 350 from the attached rotationalposition to the release rotational position. Initially, the cam servomotor 381 is in the attached rotational position and the lock servomotor 391 is in the cam rotation-preventing rotational position. Here,the lock servo motor locking extension 392 a on the end of the lockservo arm 392 engages the cam servo motor arm lock device 382 a of thecam servo motor arm 382.

Since the lock servo motor locking extension 392 a is engaged to the camservo motor arm lock device 382 a of the cam servo motor arm 382, thecam servo motor 381 cannot rotate the cam 350 from the attachedrotational position to the release rotational position(counter-clockwise from this viewpoint).

Rotating the cam 350 from the attached rotational position to therelease rotational position is a two-step process. The operator firstoperates the lock servo motor 391 to rotate the lock servo arm 392 intothe cam rotation-enabling rotational position (counter-clockwise fromthis viewpoint). Second, the operator operates the cam servo motor 381to rotate the cam 350 from the attached rotational position to therelease rotational position (counter-clockwise from this viewpoint).

FIGS. 12A-12C, described below, show how rotation of the cam from theattached rotational position to the release rotational position causesthe fixed-wing aircraft to release from the cam.

The foot 355 controls the extent to which the cam 350 can rotate. Thefoot 355 is oriented such that when the cam 350 rotates a certain amountin a first direction relative to the saddle base bracket 310, the foot355 contacts the saddle base bracket 310 and prevents the cam 350 fromrotating any further in that first direction. Similarly, when the cam350 rotates a particular amount in a second opposite direction relativeto the saddle base bracket 310, the foot 355 contacts the saddle basebracket 310 and prevents the cam 350 from rotating any further in thatsecond direction. The foot 355 is angled to stop the cam 350 fromrotating before it exerts an undue force on the cam rotation controllink 386, and by extension the cam motor arm 382 and the cam motor shaft381 a.

1.2 Rotor Arm Modules

The rotor arm modules 400 a to 400 d are mechanically attachable to andmechanically lockable to the hub module 200 and include: (1) the eightrotors of the multicopter 10; (2) the eight rotor motors that drivethese rotors; (3) gear reduction trains that couple the rotor motors totheir corresponding rotors; and (4) locking assemblies that lock therotor arm modules 400 a to 400 d to the hub module 100.

FIGS. 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H, 5I, and 5J show the first rotorarm module 400 a or components thereof. The other rotor arm modules 400b, 400 c, and 400 d are similar to the first rotor arm module 400 a andare therefore not separately shown or described.

As best shown in FIGS. 5A, 5B, 5H, and 5J, the first rotor arm module400 a includes: (1) a generally rectangular hollow elongated rotor arm410 a; (2) a generally rectangular hollow rotor arm extension 410 b; (3)a locking assembly 420; (4) a male blind mate connector 431; (5) upperand lower rotor motor assemblies 460 a and 460 b; and (6) a rotorassembly 470.

The rotor arm extension 410 b is attached to the rotor arm 410 a suchthat part of the rotor arm extension 410 b is disposed within the rotorarm 410 a and the remainder of the rotor arm extension 410 b extendsfrom the rotor arm 410 a. The locking assembly 420 is attached to theunderside of the rotor arm 410 a near the end of the rotor arm 410 afrom which the rotor arm extension 410 b extends. The male blind mateconnector 431 is attached to the end of the rotor arm 410 a from whichthe rotor arm extension 410 b extends. The upper and lower rotor motorassemblies 460 a and 460 b and the rotor assembly 470 are attached tothe rotor arm 410 a in a manner described in detail below.

Although not shown, the open end of the rotor arm 410 a opposite the endfrom which the rotor arm extension 410 b extends forms a first frontlanding gear extension module receiving socket that can receive thefirst front landing gear extension module 500 a, as described below.

As best shown in FIGS. 5A, 5B, 5C, 5D, 5E, and 5F, the male blind mateconnector 431—along with its counterpart female blind mate connector 231a of the hub module 100—facilitate: (1) mechanical attachment of thefirst rotor arm module 400 a to the hub module 100; (2) electrical powerflow from the battery(ies) 260 a, 260 b, 260 c, and/or 260 d to theupper and lower rotor motors 465 a and 465 b of the first rotor armmodule 400 a; and (3) communication between the ESCs 265 a and 265 btheir corresponding upper and lower rotor motors 465 a and 465 b.

The male blind mate connector 431 includes a plurality of pins 431 aconfigured to mate with the pin receptacles of the female blind mateconnector 231 a. Although not shown for clarity, the male blind mateconnector 431 and, particularly, the pins 431 a, are electricallyconnected to the corresponding upper and lower rotor motors 465 a and465 b via wiring. In this example embodiment, the male blind mateconnector 431 includes 12 pins 431 a, six of which are connected to theupper rotor motor 465 a via wiring and the other six of which areconnected to the lower rotor motor 465 b via wiring. In this exampleembodiment, each motor only requires three motor leads to properlyfunction, but the multicopter 10 includes two motor leads for each motorpole. By using two motor leads per motor pole, the multicopter 10eliminates single-point failures (i.e., both leads would have to failrather than just a single lead for the motor to fail).

To attach the rotor arm module 400 a to the hub module 100, an operatorinserts the rotor arm extension 410 b into the first rotor arm modulereceiving socket 214 of the hub module 100 and slides the rotor armmodule 400 a toward the hub module 100 with enough force to mate thepins of the male blind mate connector 431 with the pin receptacles ofthe female blind mate connector 231 a of the hub module 100.

As best shown in FIGS. 5C, 5D, 5E, and 5F, the locking assembly 420includes a drawcatch 420 a and a drawcatch lock 420 b that: (1)facilitate attaching the first rotor arm module 400 a to the hub module100; (2) lock the first rotor arm module 400 a to the hub module 100;and (3) facilitate detachment of the first rotor arm module 400 a fromthe hub module 100.

As best shown in FIG. 5C, the drawcatch 420 a includes: (1) a base 421;(2) a lever 422; (3) a claw 423; (4) a first fastener 424 (such as aclevis pin or other suitable fastener); and (5) a second fastener 425(such as a clevis pin or other suitable fastener).

The drawcatch lock 420 b includes: (1) a base 426; (2) a lock/releasedevice 427 having a locking shelf 427 a; (3) a pin 428 (or othersuitable connector); and (4) a compression spring 429 (or other suitablebiasing element).

The base 421 is attached to the underside of the rotor arm 410 a. Thelever 422 is pivotably connected at one end to the base 421 via thefirst fastener 424. The other end of the lever 422 includes a handle 422a. The claw 423 is pivotably connected at one end to the lever 422 viathe second fastener 425. The other end of the claw includes a latchplate engager 423 a.

The base 426 is attached to the underside of the rotor arm 410 a. Thelock/release device 427 is pivotably connected to the base 426 via thepin 428. The compression spring 429 is disposed between the base 426 andthe lock/release device 427 and retained in place via cavities and/orprojections defined in or extending from these components (not shown).

The lock/release device 427 is rotatable about the pin 428 from a lockrotational position to a release rotational position. The compressionspring 429 biases the lock/release device 427 to the lock rotationalposition. To rotate the lock/release device 427 from the lock rotationalposition to the release rotational position, the operator pushes thelock/release device 427 inward with enough force to overcome thespring-biasing force and compress the compression spring 429.

The operator uses the locking assembly 420 to lock the male blind mateconnector 431 with the female blind mate connector 231 a as follows. Theoperator rotates the handle 422 a of the lever 422 around the firstfastener 424 toward the latch plate 237 on the hollow support 210 a ofthe hub module 100 and engages the claw engager 238 of the latch plate237 with the latch plate engager 423 a of the claw 423. The operatorthen rotates the handle 422 a around the first fastener 424 and towardthe lock/release device 427 until the handle 422 a contacts thelock/release device 427. Continued rotation of the lever 422 forces thelock/release device 427 inward, which overcomes the spring-biasing forceand begins compressing the compression spring 429. This causes thelock/release device 427 to being rotating to the release rotationalposition. Once the handle 422 rotates past the locking shelf 427 a, thespring-biasing force of the compression spring 429 causes thelock/release device 427 to rotate back to the lock rotational position.At this point, the locking shelf 427 a prevents the handle 422 fromrotating back toward the latch plate 237, and the first rotor arm module400 a and the hub module 100 are locked together.

In addition to using the locking assembly 420 to lock the first rotorarm module 400 a to the hub module 100, the operator can use the lockingassembly 420 to facilitate mating the male blind mate connector 431 withthe female blind mate connector 231 a. If the male blind mate connector431 and the female blind mate connector 231 a are only partially mated(or not mated at all) and the latch plate engager 423 a of the claw 423is engaged to the claw engager 238 of the latch plate 237, rotating thehandle 422 a of the lever 422 around the first fastener 424 toward thelock/release device 427 to lock the handle 422 a will pull the firstrotor arm module 400 a and the hub module 100 toward one another andcause the male blind mate connector 431 to mate with the female blindmate connector 231 a.

As shown in FIGS. 5D and 5E, the operator reverses this process tounlock the first rotor arm module 400 a from the hub module 100. Theoperator pushes the lock/release device 427 inward with enough force toovercome the spring-biasing force and to compress the compression spring429, which causes the lock/release device 427 to rotate to the releaserotational position. This frees the handle 422 a to rotate. Once thehandle 422 a rotates past the locking shelf 427 a, the operator rotatesthe handle 422 a of the lever 422 around the first fastener 424 towardthe latch plate 237 and disengages the latch plate engager 423 a of theclaw 423 from the claw engager 238 of the latch plate 237.

At this point, the operator can either physically pull the first rotorarm module 400 a and the hub module 100 apart to separate the male andfemale blind mate connectors 431 and 231 a or use the locking assembly420 to aid in detachment. When using the locking assembly 420 to aid indetachment, as shown in FIG. 5F, after disengaging the latch plateengager 423 a from the claw engager 238, the operator continues rotatingthe handle 422 a toward the latch plate 237 until the latch plateengager 423 a contacts the backstop 239 of the latch plate 237.Afterward, continued rotation of the handle 422 a toward the latch plate237 causes the latch plate engager 423 a to impose a pushing forceagainst the backstop 239, which forces the first rotor arm module 400 aand the hub module 100 apart.

Turning to the upper and lower rotor motor assemblies 460 a and 460 band the rotor assembly 470 a, the upper and lower rotor motors 465 a and465 b of the upper and lower motor assemblies independently driverespective upper and lower rotors 475 a and 475 b via separate gearreduction trains.

As best shown in FIGS. 5G and 5H, the upper rotor motor assembly 460 aincludes: (1) an upper rotor motor mount 461 a, (2) an upper bearingspider 462 a, (3) an upper pinion 463 a, (4) upper bearings 464 a, (5)the upper rotor motor 465 a, (6) an upper bearing 466 a, (7) an upperbearing cup 467 a, (8) an upper two-piece cooling fan collar 490 a, and(9) an upper rotor motor cooling fan 495 a.

The upper rotor motor 465 a is attached to the upper rotor motor mount461 a. The bearing spider 462 a is attached to the upper rotor motormount 461 a. The upper bearings 464 a are disposed on the motor shaft(not labeled) of the upper rotor motor 465 a. The upper drive pinion 463a is disposed on the upper bearings 464 a and on the motor shaft of theupper rotor motor 465 a such that the upper drive gear 463 a rotateswith the motor shaft. The upper bearing 466 a within the upper bearingcup 467 a is disposed on the motor shaft of the upper rotor motor 465 a.The upper bearing cup 467 a is attached to the upper bearing spider 462a. The upper rotor motor cooling fan 495 a is press-fit around thebottom of the upper rotor motor 465 a and held in place via the uppertwo-piece cooling fan collar 490 a.

The lower rotor motor assembly 460 b includes: (1) a lower rotor motormount 461 b, (2) a lower bearing spider 462 b, (3) a lower pinion 463 b,(4) lower bearings 464 b, (5) the lower rotor motor 465 b, (6) a lowerbearing 466 b, (7) a lower bearing cup 467 b, (8) a lower two-piececooling fan collar 490 b, and (9) a lower rotor motor cooling fan 495 b.

The lower rotor motor 465 b is attached to the lower rotor motor mount461 b. The lower bearing spider 462 b is attached to the lower rotormount 461 b. The lower bearings 464 b are disposed on the motor shaft(not labeled) of the lower rotor motor 465 b. The lower pinion 463 b isdisposed on the lower bearings 464 b and on the motor shaft of the lowerrotor motor 465 b such that the lower pinion 463 b rotates with themotor shaft. The lower bearing 466 b within the lower bearing cup 467 bis disposed on the motor shaft of the lower rotor motor 465 b. The lowerbearing cup 467 b is attached to the lower bearing spider 462 b. Thelower rotor motor cooling fan 495 b is press-fit around the bottom ofthe lower rotor motor 465 a and held in place via the lower two-piececooling fan collar 490 b.

The upper cooling fan collar 490 a and the upper rotor motor cooling fan495 a are shown in detail in FIG. 5I. The lower cooling fan collar 490 band the lower rotor motor cooling fan 495 b are similar to the uppercooling fan collar 490 a and the upper rotor motor cooling fan 495 b andare therefore not separately shown or described.

The upper rotor motor cooling fan 495 a includes a generally annularbody that defines a plurality of cooling fan openings 496 a through itsside walls (not labeled). A collar connection lip 497 a extends upwardfrom body and radially outward. A generally annular motor mounting shelf498 a extends radially inward from the bottom of the body. A pluralityof motor seats 499 a extend upward from the motor mounting shelf 498 a.

The upper cooling fan collar 490 a includes two identical collar halves491 a having generally half-annular bodies. An upper rotor motor matingsurface 492 a that extends around the (half) circumference of the collarhalf 491 a is grooved to correspond with and mate with grooves on theexterior of the upper rotor motor 465 a. A lip retaining chamber 493 athat extends around the (half) circumference of the collar half 491 a isshaped to receive and retain the lip 497 a of the upper rotor motorcooling fan 495 a.

The bottom of the upper rotor motor 465 a is disposed within the spacedefined by the inner cylindrical surface of the cooling fan 495 a suchthat the bottom of the upper rotor motor 465 a contacts the motor seats499 a. The cooling fan openings 496 a of the cooling fan 495 a aregenerally aligned with corresponding cooling fan openings of the upperrotor motor 465. The collar halves 491 are fit onto the upper rotormotor 465 a and the cooling fan 495 a such that: (1) the lip retainingchambers 493 a of the collar halves 491 receive the lip 497 a of theupper rotor motor cooling fan 495 a; and (2) the upper rotor motormating surfaces 492 a of the collar halves 491 mate with the grooves onthe exterior of the upper rotor motor 465 a. Two fasteners (not labeled)attach the collar halves 491 a to each other to prevent separation.

The cooling fans solve two problems: limited motor power output due tooverheating and motors falling apart. First, the power output of therotor motors depends to a certain extent on cooling—power outputgenerally decreases the hotter the rotor motors get. The cooling fansenlarge the radius of the cooling fan openings of the rotor motors. Theincreased radius drives cooling air at a greater flow rate, whichimproves cooling and allows motors to be used safely at increased loadswithout fear of failure.

Second, the flux rings of the rotor motors are typically glued onto theend caps of the rotor motors. This attachment is not secure due to thetemperatures the rotor motors reach and the vibrations that occur duringflight. The cooling fan collars double as redundant load paths for themotor flux rings since they mechanically engage the grooves on theexterior of the upper rotor motor, which eliminates the chance of theflux ring working its way off of the end cap.

As best shown in FIG. 5J, the rotor assembly 470 includes a spindle 470a and the following components rotatably mounted to the spindle 470 a:(1) an upper retaining ring 471 a, (2) a lower retaining ring 471 b, (3)upper bearings 472 a and 477 a, (4) lower bearings 472 b and 477 b, (5)upper bearing cups 473 a and 478 a, (6) lower bearing cups 473 b and 478b, (7) an upper torque tube 474 a, (8) a lower torque tube 474 b, (9) anupper rotor 475 a, (10) a lower rotor 475 b, (11) an upper driven gear476 a, (12) a lower driven gear 476 b, (13) an upper spacer 479 a, and(14) a lower spacer 479 b.

Turning to the upper portion of the rotor assembly 470, the bearing 472a is disposed within the bearing cup 473 a, which is fixedly attached tothe top of the rotor 475 a. The torque tube 474 a is fixedly attached atone end to the underside of the rotor 475 a and at the other end to topof the driven gear 476 a. The bearing 477 a is disposed within thebearing cup 478 a, which is fixedly attached to the underside of thedriven gear 476 a. The spacer 479 a is disposed between the bearing 477a and the upper rotor motor mount 461 a. The upper retaining ring 471 ais seated in a groove defined around the spindle 470 a and preventsthese components from sliding off of the spindle 470 a.

Turning to the lower portion of the rotor assembly 470, the bearing 472b is disposed within the bearing cup 473 b, which is fixedly attached tothe bottom of the rotor 475 b. The torque tube 474 b is fixedly attachedat one end to the top of the rotor 475 b and at the other end tounderside of the driven gear 476 b. The bearing 477 b is disposed withinthe bearing cup 478 b, which is fixedly attached to the top of thedriven gear 476 b. The spacer 479 b is disposed between the bearing 477b and the lower rotor motor mount 461 b. The lower retaining ring 471 bis seated in a groove defined around the spindle 470 a and preventsthese components from sliding off of the spindle 470 a.

The spindle 470 a extends through two vertically aligned spindlereceiving openings (not labeled) defined through the rotor arm 410 a.This prevents the spindle 470 a from substantially translating relativeto the rotor arm 410 a. And since all of the components of the upper andlower motor assemblies 460 a and 460 b and the rotor assembly 470 areattached to the spindle 470 a (directly or indirectly), the fact thatthe spindle 470 a extends through the spindle receiving openings definedthrough the rotor arm 410 a prevents any of the components of the upperand lower motor assemblies 460 a and 460 b and the rotor assembly 470from substantially translating relative to the rotor arm 410 a.

To prevent the upper and lower rotor motors 465 a and 465 b (and certaincomponents attached thereto) from rotating relative to the rotor arm 410a, the upper and lower rotor motor mounts 461 a and 461 b are attachedto both an inner bracket 480 a and an outer bracket 480 b. The brackets480 a and 480 b are disposed around the rotor arm 410 a, as best shownin FIGS. 5A, 5B, and 5J.

In operation, the controller 272 and the ESC 265 a control the rate anddirection of rotation of the motor shaft of the upper rotor motor 465 a,which drives the upper pinion 463 a, which in turn drives the upperdriven gear 476 a. Since the upper driven gear 476 a is fixedly attachedto the upper rotor 475 a without any further gear reduction, the upperrotor 475 a rotates at the same rate as and in the same rotationaldirection as the upper driven gear 476 a. Similarly, the controller 272and the ESC 265 b control the rate and direction of rotation of themotor shaft of the lower rotor motor 465 b, which drives the lowerpinion 463 b, which in turn drives the lower driven gear 476 b. Sincethe lower driven gear 476 b is fixedly attached to the lower rotor 475 bwithout any further gear reduction, the lower rotor 475 b rotates at thesame rate as and in the same rotational direction as the lower drivengear 476 b.

In this embodiment, the upper and lower rotors are generally the samesize and shape. In another embodiment, the lower rotors are larger than(such as about 7% larger than) the upper rotors to compensate for thefact that the lower rotors operate in the upper rotors' downwash.Running larger lower rotors is one way to improve load sharing of upperand lower motors of a multicopter with counter-rotating blades. Anotherway to improve load sharing is to select a lower gear-reduction for thelower rotors. Yet another way is to select motors with higher KV(rpm/volt) values. Yet another way is to select lower rotors withcoarser pitch.

1.3 Front Landing Gear Extension Modules and Landing Gear Modules

FIGS. 6A and 7A show the first front landing gear extension module 500 aand the first front landing gear module 600 a, respectively. The frontlanding gear modules (along with the rear landing gear modules,described below) support the multicopter 10 when assembled but notflying, and facilitate launch and landing of the multicopter 10 withoutdamaging the multicopter 10. The front landing gear extensions are usedto attach the front landing gear to the respective rotor arm modules,and also enable the front landing gear to move relative to the rotor armmodules to prevent rotor rotation in certain instances.

The second front landing gear extension module 500 b and the secondfront landing gear module 600 b are similar to the first front landinggear extension module 500 a and the first front landing gear module 600a and are therefore not separately shown or described.

The first front landing gear extension module 500 a includes a generallyrectangular hollow support 510 a, a landing gear module securing device520 attached at one end of the support 510 a, and a front landing gearlocking device 530 (which is a cam lever lock in this embodiment but canbe any suitable locking device) attached to the landing gear modulesecuring device 520.

The first front landing gear module 600 a includes a generallycylindrical leg 610, a generally semicircular foot 620 attached to abottom end of the leg 610, and a collar 630 attached near the top end ofthe leg 610 via a fastener 632 (such as a set screw).

The front landing gear locking device 530 enables an operator to attachthe first front landing gear module 600 a to the first front landinggear extension module 500 a. To do so, the operator unlocks the frontlanding gear locking device 530, inserts the first front landing gearmodule 600 a into the landing gear module securing device 520 until thecollar 630 is disposed within the landing gear module securing device520, and re-locks the front landing gear locking device 530. Theoperator reverses this process to detach the first front landing gearmodule 600 a from the first front landing gear extension module 500 a.

The operator attaches the first front landing gear extension module 500a to the first rotor arm module 400 a by inserting the end of thesupport 510 a opposite the end to which the landing gear module securingdevice 520 is attached into the front landing gear extension modulereceiving socket of the first rotor arm module 400 a. The operator thenlocks the first front landing gear extension module 500 a into place,such as using suitable fasteners.

Although not shown, the operator can move the front landing gear modulefurther radially inward or further radially outward by sliding thesupport of the front landing gear extension module further into orfurther out of the rotor arm of the corresponding rotor arm module. Thisenables the operator to move the front landing gear module from a firstposition in which the front landing gear module is clear of the rotorsradially inward to a second position in which the rotors contact thefront landing gear module. When in the second position, the frontlanding gear module prevents the rotors from rotating.

1.4 Rear Landing Gear Extension Modules and Landing Gear Module

FIGS. 6B and 7B show the first rear landing gear extension module 500 cand the first rear landing gear module 600 c, respectively. The rearlanding gear modules (along with the front landing gear modules,described above) support the multicopter 10 when assembled but notflying, and facilitate launch and landing of the multicopter 10 withoutdamaging the multicopter 10. The rear landing gear modules are shapedsuch that they act as vertical stabilizers (or fins) during flight,ensuring that the front of the multicopter 10 (and the nose of thefixed-wing aircraft 20 a, if attached thereto) points generally into theairflow. The rear landing gear extensions are used to attach the rearlanding gear to the respective rotor arm modules, and also enable therear landing gear to move relative to the rotor arm modules to preventrotor rotation in certain instances.

The second rear landing gear extension module 500 d and the second rearlanding gear module 600 d are similar to the first rear landing gearextension module 500 c and the first rear landing gear module 600 c andare therefore not separately shown or described.

The first rear landing gear extension module 500 c is a rectangularhollow support 510 c.

The first rear landing gear module 600 c includes a body having agenerally triangular cross-section that tapers from front to back. Thebody includes two side surfaces 650 a and 650 b and a front surface 650c joining the side surfaces 650 a and 650 b. The side surfaces 650 a and650 b are substantially longer than the front surface 650 c is wide. Thebody transitions at its bottom into a generally circular foot 670. Arear landing gear extension module receiving socket is defined by ahollow rectangular support 680 extending through the body.

The operator attaches the first rear landing gear extension module 500 cto the third landing gear module 600 c by inserting one end of thesupport 510 c of the first rear landing gear extension module 500 c intothe rear landing gear extension module receiving socket of the support680. The operator then locks the first rear landing gear extensionmodule 500 c into place, such as using suitable fasteners.

The operator attaches the first rear landing gear extension module 500 cto the third rotor arm module 400 c by inserting the end of the support510 c of the first rear landing gear extension module 500 c opposite theend to which the first rear landing gear module 600 c is attached intothe rear landing gear extension module receiving socket of the thirdrotor arm module 400 c. The operator then locks the first rear landinggear extension module 500 c into place, such as using suitablefasteners.

Once attached, the rear landing gear modules are oriented such that theside surfaces of the rear landing gear modules are substantially alignedwith the saddle side brackets 320 a and 320 b of the saddle 300, as bestshown in FIG. 1B. When the fixed-wing aircraft 20 a is attached to themulticopter 10, these side surfaces of the rear landing gear modules aresubstantially parallel to a plane containing the roll axis of thefuselage of the fixed-wing aircraft 20 a. The relatively long length ofthese side surfaces of the rear landing gear modules and their placementwell-aft of the center-of-lift of the multicopter 10 cause the rearlanding gear module to act as fins. This weather vane effect ensuresthat the nose of the fixed-wing aircraft 20 a is oriented into theairflow when airborne. Good flow alignment is critically important forspin avoidance at the moment the multicopter 10 releases the fixed-wingaircraft 20 a, when the fixed-wing aircraft 20 a may be operatingwell-below stall speed.

In certain embodiments, one or more of the landing gear modules includesa shock absorber.

1.5 Separately Powered Upper and Lower Rotor Motors

As noted above, four batteries 260 a to 260 d power the multicopter 10,though in other embodiments a different quantity of batteries and/ordifferent type(s) of batteries power the multicopter. In otherembodiments, any suitable power source(s), such as a fuel-based powersource or a solar-based power source, may be used instead of or alongwith batteries.

In this embodiment, a first pair of batteries 260 a and 260 b areconnected in series and a second pair of batteries 260 c and 260 d areconnected in series. Here, the first pair of batteries 260 a and 260 bpower the upper rotor motors and do not power the lower rotor motors,while the second pair of batteries 260 c and 260 d power the lower rotormotors and do not power the upper rotor motors. This configurationensures that, if one pair of batteries fails, the multicopter 10 isoperable in a quadcopter mode with either all four upper rotor motors(if the second pair of batteries 260 c and 260 d fails) or all fourlower rotor motors (if the first pair of batteries 260 a and 260 bfails).

The multicopter 10 also includes a gang circuit that connects the twopairs of batteries in parallel to enable a single charger connected toone of the pairs of batteries to also charge the other pair ofbatteries. The gang circuit is overload-protected and includes anautomatically resetting circuit breaker. The gang circuit is beneficialbecause it reduces charging time, allowing an operator to recharge bothbatteries in parallel when only one charger is available.

1.6 Multicopter Operating Modes

The multicopter 10 is operable in one of two throttle modes: NORMALthrottle mode and TENSION throttle mode. The multicopter 10 is operablein three different flight modes: ALTHOLD flight mode, LOITER flightmode, and RTL flight mode. The multicopter 10 is operable in ahalf-power mode to, in certain situations, improve response and savepower. The basic functionality of each operating mode is describedbelow. The operator can toggle between these operating modes usingsuitable switches, a touch screen, or any other suitable device on theR/C controller.

On a typical R/C controller including left and right joysticks, the leftjoystick is typically used for throttle, while the right joystick istypically used for left/right and for/aft station-keeping of theaircraft.

1.6.1 SIMPLE Control Mode

SIMPLE control mode simplifies horizontal control by tying the R/Ccontroller's right stick commands to geo-referenced coordinates. Themulticopter 10 always operates in SIMPLE control mode, regardless ofwhich of the three flight modes the multicopter 10 employs. Under SIMPLEcontrol mode, forward right stick deflection drives the multicopter 10in the direction in which the multicopter 10 was pointed at the instantit was armed, regardless of its yaw orientation during flight. Putdifferently, if the multicopter 10 was pointed North when armed but,while hovering for instance, the multicopter 10 rotated about its yawaxis such that its nose is pointed East, forward right stick deflectionstill drives the multicopter 10 North. While the operator may use theleft stick to rotate the multicopter 10 about the yaw axis, this(rudder) input is rarely needed for launch or retrieval of thefixed-wing aircraft 20 a. The rear landing gear modules ensure themulticopter 10 is pointed into the relative wind (like a weathervane),so the operator need not worry about aligning the fuselage with airflow.

1.6.2 TENSION Throttle Mode

When the multicopter 10 operates in TENSION throttle mode, the humanoperator has direct control over the throttle. The multicopter 10 canonly be operated in TENSION throttle mode when it is operated in eitherALTHOLD or LOITER flight modes. That is, the multicopter 10 cannot beoperated in TENSION throttle mode when operated in RTL flight mode.TENSION throttle mode converts throttle stick inputs to direct throttlecommands, which is primarily useful for tensioning the flexible capturetether 5000 during retrieval. An astute operator will climb at acontrolled rate by feathering the throttle in TENSION throttle mode, hewill slow high ascent as the tether pulls tight (described below), andthen he maintains light tether tension, keeping the line straight as thefixed-wing aircraft approaches. The straight line allows human observersto confirm that the line will be swept by the fixed-wing leading edgeand the capture is on-target. At impact, the operator increases throttleto arrest the fixed-wing aircraft's horizontal motion and minimizealtitude loss. Then he feathers the throttle back to lower the aircraftto the ground.

1.6.3 NORMAL Throttle Mode

In Normal throttle mode, the controller interprets joystick commands asdesired rate commands and applies whatever throttle is needed to achievethat climb or descent rate. When tethered to the ground the altitudecontroller very abruptly increases throttle to maximum (when its desiredaltitude is above current altitude) or it plummets to minimum throttle(when desired altitude is below current altitude) without regard forjoystick position. This behavior makes it impossible for the humanoperator to regulate tether tension directly. Direct throttle control,offered by TENSION throttle mode, disables the altitude controller. Inthis mode, altitude is controlled strictly by tether length. In TensionMode, the human operator controls tether tension directly, with throttleinputs, and the controller responds with lift-producing motor commandsthat are roughly proportional to commanded throttle position. By thistechnique, the retrieval process enjoys improved finesse and precisecontrol without overworking the multicopter motors and batteries.

1.6.4 ALTHOLD Flight Mode

ALTHOLD flight mode converts throttle commands (left stick, verticalaxis) to vertical rate commands. When operating in the ALTHOLD flightmode, the multicopter 10 will attempt to maintain current altitude whenthe left stick is in the middle position. The multicopter 10 willattempt to climb at up to 5 meters per second (or any other suitablerate) when the left stick is pushed up to max. The multicopter 10 willdescend at up to 5 meters per second (or any other suitable rate) whenthe left stick is pulled to min. ALTHOLD flight mode converts rightstick commands to lean angle, with maximum right stick deflectioncorresponding to 30 degrees (or any other suitable angle). Whenoperating in ALTHOLD flight mode, the multicopter 10 will maintain zerolean when the right stick is in the middle position and will be blowndownwind. If the fixed-wing aircraft 20 a is mated to the multicopter 10and producing thrust, this thrust will drive the multicopter 10 forwardunopposed by lean angle. ALTHOLD flight mode does not depend on GPS forcontrol, and works equally well indoors and in all locations where GPSreception is spotty or denied. ALTHOLD flight mode uses a compass fornavigation, which means “SIMPLE MODE” works equally well without the useof GPS. Consequently, the operator simply pushes the right joystickgently into the wind for station-keeping, fully into the wind to executea “dash” maneuver (for launch/release), and he will relax the rightstick to allow the aircraft to drift downwind to return home after adash. Finally, the operator will deflect the right stick opposite theaircraft's ground track to minimize ground speed just before touch-down.

1.6.5 LOITER Flight Mode

LOITER flight mode behaves like ALTHOLD flight mode in the verticaldirection (i.e., converts throttle commands to vertical rate commands).Similarly, LOITER flight mode converts right stick inputs to horizontalrate commands. When operating in LOITER flight mode, the multicopter 10attempts to maintain its current horizontal position over the Earth whenthe right stick is in the middle position. Maximum right stickdeflection drives the multicopter 10 in the corresponding direction atup to 20 meters per second ground speed (or any suitable rate) or themaximum achievable speed against true wind, whichever is less. LOITERflight mode depends on GPS to close feedback loops around latitude andlongitude positions. The controller 272 will automatically switch itselffrom LOITER flight mode to ALTHOLD flight mode when GPS reception isunacceptable, and will not allow a human operator to arm in LOITERflight mode when GPS reception is unacceptable.

1.6.6 RTL Flight Mode

Return to Launch (RTL) flight mode autonomously returns the multicopter10 to its home position—i.e., the place on Earth where it was lastarmed. When operating in RTL mode, left stick inputs are ignored exceptwhen executing a SHUT DOWN command, and right stick inputs are used onlyduring the final (vertical) descent phase. The operator uses the rightstick to “nudge” the multicopter 10 a designated distance away from thestorage and launch system 2000 to avoid interference at touchdown.Multicopter response to these nudge maneuvers will be similar to rightstick inputs in LOITER flight mode, and the operator should execute thembefore the aircraft descends below 5 meters (or any other suitabledistance) above ground level. To avoid human operator-inducedoscillations and to minimize ground speed, the human operator's fingersshould be kept off the control sticks during final descent and touchdownin RTL mode.

1.6.7 Half-Power Mode

When operating in half-power mode, the multicopter 10 shuts down half ofits rotors—either the lower rotors or the upper rotors—and operatesusing only the remaining half of the rotors. Half-power mode istypically used after the multicopter 10 releases the fixed-wing aircraft20 a and the multicopter 10 is returning to its home position. Using alleight rotors to fly just the multicopter 10, which is relatively lightwhen not carrying the fixed-wing aircraft 20 a, provides too much powerand induces sluggish response to operator commands. This is not ideal,especially when launching the multicopter 10 from an area full ofobstructions that the multicopter 10 must deftly avoid on its way backto its home position. Operating in half-power mode in these instancesprovides a more appropriate amount of power and enables more preciseresponses to operator commands.

2. Storage and Launch System

The storage and launch system 2000 is shown in FIGS. 8A, 8B, 8C, 8D, 8E,8F, 8G, 8H, and 8I. The storage and launch system 2000 is usable tocompactly store the modular multicopter 10 in a single container afterdisassembly into the 13 modules and to facilitate launch of thefixed-wing aircraft 20 a into free, wing-borne flight by acting as alaunch mount for the fixed-wing aircraft 20 a.

To facilitate storage of the multicopter 10 in a single container(including a container top 2000 a and a container bottom 2000 b), thestorage and launch system 2000 includes: (1) a launch-assist assembly2100 to which the front landing gear modules 600 a and 600 b areattachable; (2) a rotor arm module and rear landing gear module storagedevice 2200 to which the rotor arm modules 400 a to 400 d and the rearlanding gear modules 600 c and 600 d are attachable; and (3) a hubmodule storage tray 2300 to which the hub module 100 is attachable.

To facilitate launch of the fixed-wing aircraft 20 a, the launch-assistassembly 2100 is movable from a storage position into a launch positionand includes certain elements on which the fixed-wing aircraft can bemounted and other elements that retain the fixed-wing aircraft 20 a in alaunch orientation before launch. Example embodiments of each of theseelements are described below, followed by a description of an examplemethod of storing the multicopter 10 using these example embodiments ofthe elements.

2.1 Launch-Assist Assembly

The launch-assist assembly 2100 is attached to the container bottom 2000b and is one element of the storage and launch system 2000 thatfacilitates launch of the fixed-wing aircraft 20 a. The launch-assistassembly 2100 is movable from a position in which it lies substantiallyflat along the floor of the container bottom 2000 a to enable storage ofthe multicopter 10 to a launch position in which it is generallyspaced-apart from and upwardly angled relative to the floor of thecontainer bottom 2000 a to facilitate launch of the fixed-wing aircraft20 a.

As best shown in FIG. 8C, the launch-assist assembly 2100 includes: (1)first and second base brackets 2102 a and 2102 b; (2) first and secondfront legs 2104 a and 2104 b; (3) first and second rear legs 2106 a and2106 b; (4) a tray 2108; (5) first and second front landing gear moduleretainers 2110 a and 2110 b; (6) a storage device lock engager 2112; (7)front and rear stabilizing brackets 2114 a and 2114 b; (8) first andsecond lockable gas springs 2116 a and 2116 b; and (9) anaircraft-engaging bracket 2120.

The first and second base brackets 2102 a and 2102 b are attached to thefloor of the container bottom 2000 a near one end. The first front leg2104 a is pivotably attached at one end to the front end of the firstbase bracket 2102 a and pivotably attached at the other end to the tray2108. Similarly, the second front leg 2104 b is pivotably attached atone end to the front end of the second base bracket 2102 b and pivotablyattached at the other end to the tray 2108. The first rear leg 2106 a ispivotably attached at one end to the rear end of the first base bracket2102 a and pivotably attached at the other end to the tray 2108.Similarly, the second rear leg 2106 b is pivotably attached at one endto the rear end of the second base bracket 2102 b and pivotably attachedat the other end to the tray 2108. The front stabilizing bracket 2114 ais attached to and extends between the first and second front legs 2104a and 2104 b, and the rear stabilizing bracket 2114 b is attached to andextends between the first and second rear legs 2106 a and 2106 b. Thefirst lockable gas spring 2116 a is pivotably attached at one end to thefirst base bracket 2102 a between the first front leg 2104 a and thefirst rear leg 2106 a and pivotably attached at the other end to thefirst front leg 2104 a between the first base bracket 2102 a and thetray 2108. Similarly, the second lockable gas spring 2116 b is pivotablyattached at one end to the second base bracket 2102 b between the secondfront leg 2104 b and the second rear leg 2106 b and pivotably attachedat the other end to the second front leg 2104 b between the second basebracket 2102 b and the tray 2108. The storage device lock engager 2112,the first and second front landing gear module retainers 2110 a and 2110b, and the aircraft engaging bracket 2120 are attached to the tray 2108.

The aircraft engaging bracket 2120 includes two spaced-apart generallyparallel sides 2121 and 2123 having wing engaging surfaces 2121 a and2123 a, respectively, and a back 2122 transverse (such as generallyperpendicular) to, extending between, and connecting the sides 2121 and2123. A fuselage-retaining assembly 2130 is rotatably mounted to theback plate 2122.

The above-described pivotable attachments enable the launch assistassembly 2100 to move from: (1) a storage position in which the firstand second front legs 2104 a and 2104 b, the first and second back legs2106 a and 2106 b, and the tray 2108 lay substantially flat along thefloor of the container bottom 2000 a (as best shown in FIGS. 8A and 8B);to (2) a launch position in which the first and second front legs 2104 aand 2104 b and the first and second back legs 2106 a and 2106 b extendupward from the floor of the container bottom 2000 a such that the tray2108 is spaced-apart from and upwardly angled relative to the floor ofthe container bottom 2000 a (as best shown in FIGS. 8C and 8D) (andvice-versa). The operator can lock the launch assist assembly 2100 inthe launch position by locking the first and second lockable gas springs2116 a and 2116 b.

When in the launch position, the launch assist assembly 2100 facilitateslaunch of the fixed-wing aircraft 20 a by orienting the fixed-wingaircraft 20 a in a desired launch orientation and retaining thefixed-wing aircraft 20 a in that orientation until the operator desiresto launch the fixed-wing aircraft 20 a. As best shown in FIG. 8D, inpreparation for launch, the operator inserts the fuselage of thefixed-wing aircraft 20 a into the fuselage-retaining assembly 2130 ofthe aircraft engaging bracket 2120 and lays the wings of the fixed-wingaircraft 20 a atop the first and second wing engaging surfaces 2123 aand 2123 b of the aircraft engaging bracket 2120.

The fuselage-retaining assembly 2130 is sized to receive the fuselage ofthe fixed-wing aircraft 20 a. The fuselage-retaining assembly 2130 isconfigured such that, after it receives the fuselage, thefuselage-retaining assembly 2130 does not release the fuselage until:(1) the operator disengages a safety mechanism; and (2) a force biasingthe fuselage-retaining assembly 2130 against releasing the fuselage isovercome. This prevents undesired launch of the fixed-wing aircraft 20a.

As best shown in FIGS. 8E, 8F, and 8G, the fuselage-retaining assembly2130 includes: (1) first and second pincers 2132 and 2134; (2) first andsecond rollers 2136 and 2138 and corresponding nuts 2136 a and 2138 a;(3) a grooved clevis pin 2140 and corresponding retaining ring 2140 a,spacer 2140 b, and washer 2140 c; (4) first and second spring mountingspacers 2142 and 2144 and their corresponding fasteners 2142 a and 2144a and nuts 2142 b and 2144 b; (5) a compression spring 2146; and (6) asafety mechanism 2150.

The safety mechanism 2150 includes: (1) front and rear plates 2151 and2152; (2) fasteners 2154 a and 2154 e; (3) clevis pins 2154 b, 2154 c,and 2154 d; (4) spacers 2156 a and 2156 e; (5) a rod end 2156 b; (6) acompression spring 2158; and (7) a handle 2160.

The first and second pincers 2132 and 2134 are interchangeable, and havegenerally curved bodies that define rod end engagers 2132 a and 2134 a,respectively, along their outer edges and terminate at their lower endsin safety mechanism engagers 2132 b and 2134 b. The roller 2136 isattached via the nut 2136 a to the upper end of the first pincer 2132,and the roller 2138 is attached via the nut 2138 a to the upper end ofthe second pincer 2134. The rollers are rotatable with respect to theirrespective pincers. The first and second pincers 2132 and 2134 arepivotably connected to one another via the grooved clevis pin 2140, thespacer 2140 b, the washer 2140 c, and the retaining ring 2140 a.Although not shown, the fuselage-retaining assembly 2130 is attached tothe aircraft engaging bracket 2120 via this grooved clevis pin 2140.

In this embodiment, the first pincer is mounted on the grooved clevispin in front of the second pincer (with respect to the view shown inFIG. 8E), though in other embodiments the second pincer may be mountedin front of the first pincer without changing how the fuselage-retainingassembly operates.

As best shown in FIG. 8G, the spring mounting spacer 2142 is mounted toa backwardly extending portion of the first pincer 2132 via the fastener2142 a and the nut 2142 b. Similarly, the spring mounting spacer 2144 ismounted to a backwardly extending portion of the second pincer 2134 viathe fastener 2144 a and the nut 2144 b. The compression spring 2146 ismounted on and extends between the spring mounting spacers 2142 and2144.

The first and second pincers 2132 and 2134 are movable relative to oneanother from: (1) a fuselage-retaining orientation in which their upperends are separated a first distance that is smaller than the diameter ofthe fuselage of the fixed-wing aircraft 20 a (shown in FIGS. 8E and 8F);to (2) a fuselage-release orientation in which their upper ends areseparated a second distance that is larger than the diameter of thefuselage of the fixed-wing aircraft 20 a (not shown) (and vice-versa).Thus, when the first and second pincers 2132 and 2134 are in thefuselage-retaining orientation, the fuselage of the fixed-wing aircraftcannot escape the first and second pincers 2132 and 2134 (absent furtherseparation of the pincers), while the fuselage can escape when the firstand second pincers 2132 and 2134 are in the fuselage-releaseorientation.

The compression spring 2146 opposes separation of the first and secondpincers 2132 and 2134 and therefore biases the first and second pincers2132 and 2134 toward the fuselage-retaining orientation. Separating thefirst and second pincers 2132 and 2134 causes the backwardly extendingportions of the first and second pincers 2132 and 2134 to compress thecompression spring 2146, which causes the compression spring 2146 toexert forces on the backwardly extending portions of the first andsecond pincers 2132 and 2134 opposing that separation. Thus, to releasethe fuselage, this biasing force must be overcome.

Turning to the safety mechanism 2150, as best shown in FIG. 8E, thefront plate 2151, the rear plate 2152, and the handle 2160 are attachedto one another via: (1) the fastener 2154 a extending through an opening2152 a in the rear plate 2152, through the spacer 2156 a, through anopening 2151 a in the front plate 2151, and into the handle 2160; (2)the clevis pin 2154 b extending through an opening 2152 a in the rearplate 2152, through an opening in the rod end 2156 b, and through anopening 2151 b in the front plate 2151; (3) the clevis pin 2154 dextending through an opening 2152 d in the second plate and an opening2151 d in the front plate 2151; and (4) the fastener 2154 e extendingthrough an opening 2152 e in the rear plate 2152, through the spacer2156 e, and through an opening 2151 e in the front plate 2151.

As best shown in FIGS. 8E and 8F, the safety mechanism 2150 is pivotablyconnected to the second pincer 2134 via the clevis pin 2154 c extendingthrough an opening 2152 c in the rear plate 2152, an opening 2134 c inthe second pincer 2134, and an opening 2151 c in the front plate 2151.One end of the safety compression spring 2158 is disposed around the rodend 2156 b and the other end of the safety compression spring 2158 isdisposed around the rod end engager 2134 a of the second pincer 2134.

The safety mechanism 2150 is rotatable about the clevis pin 2134 c froman engaged rotational position in which the safety mechanism 2150prevents separation of the first and second pincers 2132 and 2134 fromthe fuselage-retaining orientation to the fuselage-release orientation(shown in FIGS. 8F and 8G) to a disengaged rotational position (notshown) in which the first and second pincers 2132 and 2134 are free toseparate from the fuselage-retaining orientation to the fuselage-releaseorientation. The safety compression spring 2158 biases the safetymechanism 2150 into the engaged rotational position.

When in the engaged rotational position, the safety mechanism 2150prevents separation of the first and second pincers 2132 and 2134 fromthe fuselage-retaining orientation to the fuselage-release orientation.Separating the first and second pincers 2132 and 2134 when the safetymechanism 2150 is in the engaged rotational position results in: (1) thesafety mechanism engager 2132 b of the first pincer 2132 engaging theclevis pin 2154 d (since the clevis pin 2154 d is in the path ofrotation of the safety mechanism engager 2132 b of the first pincer2132); and (2) the rod end engager 2134 a of the second pincer 2134engaging the rod end 2136 b. This prevents the first and second pincers2132 and 2134 from rotation relative to one another and thereforeprevents further separation of the first and second pincers 2132 and2134 to the fuselage-release orientation.

To enable the first and second pincers 2132 and 2134 to separate fromthe fuselage-retaining orientation to the fuselage-release orientation,the operator disengages the safety mechanism by rotating the safetymechanism 2150 from the engaged rotational position to the disengagedrotational position. To do so, the operator pulls the handle 2160 upwardwith enough force to overcome the spring-biasing force of thecompression spring 2158 and compress the compression spring 2158 untilthe clevis pin 2154 d is no longer in the path of rotation of the safetymechanism engager 2132 b of the first pincer 2132. At this point, thesafety mechanism 2150 is in the disengaged rotational position, and thefirst and second pincers 2132 and 2134 can separate to thefuselage-release orientation.

In certain embodiments, a safety rope, tether, wire, cable, or otherflexible member is attached to the handle (or any other suitablecomponent) of the safety mechanism to facilitate disengaging the safetymechanism. When the flexible safety member is tensioned (such as via anoperator pulling on the flexible safety member), the safety mechanismrotates from the engaged rotational position to the disengagedrotational position, thereby disengaging the safety mechanism. Theflexible safety member may be relatively long, which enables theoperator to stand a safe distance away from the fixed-wing aircraftduring the launch process and still be able to disengage the safetymechanism.

By intentionally commanding full multicopter thrust without releasingthe safety mechanism, an operator may execute a “refuse takeoff” test,which is particularly useful for confirming full-power performance ofthe complete electromechanical system without fear of flight-relatedmishap in the event that one or more components of the system shouldfail during the test.

2.2 Rotor Arm Module and Rear Landing Gear Module Storage Device

The rotor arm module and rear landing gear module storage device 2200 isshown in FIGS. 8H and 8I. The rotor arm module and rear landing gearmodule storage device 2200 is the element of the storage and launchsystem 2000 to which the rotor arm modules 400 a to 400 d and the rearlanding gear modules 600 c and 600 d can be mounted and compactlystored. The rotor arm module and rear landing gear module storage device2200 includes: (1) a base 2205; (2) a handle 2210; (3) an upper rotorarm module constraining plate 2230; (4) a lower rotor arm moduleconstraining plate 2250; and (5) a lock 2220 (which is a slide bolt inthis embodiment but can be any suitable device).

The base 2205 defines a storage device lock engager receiving cavity2205 a therethrough sized to receive the storage device lock engager2112 of the launch-assist assembly 2100. The lock 2220 is fixedlyattached to the base 2205 near the storage device lock engager receivingcavity such that the lock 2220 can engage the storage device lockengager 2112 when the storage device lock engager 2112 is received inthe storage device lock engager receiving cavity 2205 a to lock therotor arm module and rear landing gear module storage device 2200 to thelaunch assist assembly 2100.

The handle 2210 includes two opposing, spaced-apart sides 2211 and 2213and a top 2212 extending between the sides 2211 and 2213. The sides 2211and 2213 are attached to the base 2205. The side 2211 includes twosurfaces 2211 a and 2211 b each defining a rear landing gear modulereceiving cavity sized and shaped to receive a portion of one of therear landing gear modules 600 c and 600 d.

The upper rotor arm module constraining plate 2230 is attached to thehandle 2210. The upper rotor arm module constraining plate 2230 includesa plurality of surfaces 2230 a, 2230 b, 2230 c, and 2230 d each defininga rotor motor receiving cavity sized and shaped to receive a rotor motorof one of the rotor arm modules.

The upper rotor arm module constraining plate 2230 also includes aplurality of rotor arm module retainers 2241, 2242, 2243, and 2244disposed within an enclosing bracket 2240. The rotor arm module retainer2241 includes a locking tab 2241 a extending below the upper rotor armmodule constraining plate 2230 and is pivotably connected to the upperrotor arm module constraining plate 2230 via a pin 2241 b. The rotor armmodule retainer 2242 includes a locking tab 2242 a extending below theupper rotor arm module constraining plate 2230 and is pivotablyconnected to the upper rotor arm module constraining plate 2230 via apin 2242 b. The rotor arm module retainer 2243 includes a locking tab2243 a extending below the upper rotor arm module constraining plate2230 and is pivotably connected to the upper rotor arm moduleconstraining plate 2230 via a pin 2243 b. The rotor arm module retainer2244 includes a locking tab 2244 a extending below the upper rotor armmodule constraining plate 2230 and is pivotably connected to the upperrotor arm module constraining plate 2230 via a pin 2244 b.

The rotor arm module retainers are pivotable from a lock rotationalposition (shown in FIG. 8I) to a release rotational position (notshown). Suitable biasing elements (such as compression spring, notshown) bias the rotor arm module retainers to the lock rotationalposition.

The lower rotor arm module constraining plate 2250 is attached to thehandle 2210 below the upper rotor arm module constraining plate 2230.The lower rotor arm module constraining plate 2250 includes a pluralityof surfaces 2250 a, 2250 b, 2250 c, and 2250 d each defining a rotormotor receiving cavity sized and shaped to receive a rotor motor of oneof the rotor arm modules.

2.3 Hub Module Storage Tray

The hub module storage tray 2300 is shown in FIG. 8J. The hub modulestorage tray 2300 is the element of the storage and launch system 2000to which the hub module 200 is mounted for storage. The hub modulestorage tray 2300 includes a generally rectangular base 2310, a handle2320 fixedly attached to the base 2310, and four female blind mateconnector engagers 2332, 2334, 2336, and 2338 fixedly attached to thebase 2310. The female blind mate connector engagers are sized and shapedto engage the top surfaces of the female blind mate connectors 231 ofthe hub module 100.

2.4 Storing the Multicopter in the Multicopter Storage Container

To store the multicopter 10 in the container of the storage and launchsystem 2000, the operator first disassembles the multicopter 10 into the13 modules or subassemblies, as described above. The operator moves thelaunch-assist assembly into its launch position.

The operator positions the rotor arm module and rear landing gear modulestorage device 2200 atop the launch-assist assembly 2100 such that thestorage device lock engager 2112 of the launch-assist assembly 2100 isreceived in the storage device lock engager receiving cavity 2205 a. Theoperator engages the storage device lock engager 2112 with the lock 2220to lock the rotor arm module and rear landing gear module storage device2200 to the launch assist assembly 2100.

The operator slides the rotor arm module 400 a into the space betweenthe upper and lower rotor arm module constraining plates 2230 and 2250of the rotor arm module and rear landing gear module storage device 2200until: (1) the lower rotor motor is disposed within the rotor motorreceiving cavities defined by the surfaces 2230 b and 2250 b; and (2)the rotor arm module retainer 2243 locks the rotor arm module 400 a intoplace.

The operator slides the rotor arm module 400 b into the space betweenthe upper and lower rotor arm module constraining plates 2230 and 2250of the rotor arm module and rear landing gear module storage device 2200until: (1) the lower rotor motor is disposed within the rotor motorreceiving cavities defined by the surfaces 2230 d and 2250 d; and (2)the rotor arm module retainer 2242 locks the rotor arm module 400 b intoplace.

The operator slides the rotor arm module 400 c into the space betweenthe upper and lower rotor arm module constraining plates 2230 and 2250of the rotor arm module and rear landing gear module storage device 2200until: (1) the upper rotor motor is disposed within the rotor motorreceiving cavities defined by the surfaces 2230 c and 2250 c; and (2)the rotor arm module retainer 2241 locks the rotor arm module 400 c intoplace.

The operator slides the rotor arm module 400 d into the space betweenthe upper and lower rotor arm module constraining plates 2230 and 2250of the rotor arm module and rear landing gear module storage device 2200until: (1) the upper rotor motor is disposed within the rotor motorreceiving cavities defined by the surfaces 2230 a and 2250 a; and (2)the rotor arm module retainer 2244 locks the rotor arm module 400 d intoplace.

The operator inserts the front landing gear modules 600 a and 600 b intothe first and second front landing gear module retainers 2110 a and 2110b on the tray 2108 of the launch-assist assembly 2100.

The operator inserts the rear landing gear module 600 c into the rearlanding gear module receiving cavity defined by the surface 2211 b andthe rear landing gear module 600 d into the rear landing gear modulereceiving cavity defined by the surface 2211 a.

The operator places the landing gear extensions 500 a to 500 d in thecontainer bottom 2000 a behind the handle 2320 of the hub module storagetray 2300. The operator attaches the container top 2000 b to thecontainer bottom 2000 a to complete storage.

The operator inverts the hub module 100 and engages the female blindmate connector engagers 2332, 2334, 2336, and 2338 of the hub modulestorage tray 2300 with the female blind mate connectors 231 of the hubmodule 100.

The operator moves the launch-assist assembly 2100 to the storageposition.

In certain embodiments, the container top or the container bottomincludes one or more handles (such as an extendable handle) or one ormore wheels to facilitate moving the container. In certain embodiments,the container top or the container bottom includes one or more locksconfigured to lock the container top to the container bottom.

3. Anchor System

The anchor system 3000 and components thereof is shown in FIGS. 9A-9Hand 10A-10D. The anchor system 3000 is usable along with the multicopter10, the flexible capture member 5000 (described below), and theaircraft-landing structure 8000 (described below) to retrieve thefixed-wing aircraft 20 a from free, wing-borne flight. Generally, thecomponents of the anchor system 3000 operate together to impose aregulated force on the flexible capture member 5000 during thefixed-wing aircraft retrieval process. This means that the anchor system3000 is configured to regulate—i.e., maintain substantially constant—thetension in the flexible capture member 5000 while the multicopter 10 isstation-keeping relative to the anchor system 3000 in preparation forretrieval of the fixed-wing aircraft 20 a. This simplifies multicopteroperation during the fixed-wing aircraft retrieval process byeliminating the need for the multicopter operator to control thealtitude of the multicopter 10 to maintain a desired tension in theflexible capture member 5000.

The anchor system 3000 includes an anchor system base 3100, a firstmounting bracket 3200, a second mounting bracket 3300, a separatorbracket 3400, and a flexible capture member payout and retract system(not labeled). The flexible capture member payout and retract systemincludes a drum assembly 3500, a level wind system 3600, a transitionassembly 3700, and a hydraulic system 7300.

3.1 Anchor System Base and Brackets

The anchor system base 3100 serves as a mount for certain other elementsof the anchor system 3000. As best shown in FIGS. 9A-9E, the anchorsystem base 3100 includes two spaced-apart, generally parallel sides3102 and 3104 and a top 3106 transverse (such as generallyperpendicular) to, extending between, and connecting the sides 3102 and3104. As best shown in FIG. 9C, the top 3106 includes a surface 3106 athat defines a GPS antenna mounting opening through the top 3106 and asurface 3106 b that defines a lower sealing and mounting componentopening through the top 3106. The GPS antenna 3800 is attached to amounting bracket (not labeled) that extends between the sides 3102 and3104 such that the GPS antenna 3800 extends through the GPS antennamounting opening of the top 3106. As described below, a lower sealingand mounting component 8500 of the aircraft-landing structure 8000 isattachable to the top 3106 of the anchor system base 3100 via the lowersealing and mounting component mounting opening to attach theaircraft-landing structure 8000 to the anchor system base 3100.

The first and second mounting brackets 3200 and 3300 serve as mounts forthe drum assembly 3500 and part of the hydraulic system 7300. As bestshown in FIGS. 9D and 9E, the first and second mounting brackets 3200and 3300 are generally planar and include respective cylindricalsurfaces 3200 a and 3300 a that respectively define first and secondmounting openings through the first and second mounting brackets 3200and 3300. The first mounting bracket 3200 is attached to the first side3102 of the anchor system base 3100 via suitable fasteners (not shown),and the second mounting bracket 3300 is attached to the second side 3104of the anchor system base 3100 via suitable fasteners (not shown). Theseparator bracket 3400 is attached to and extends between the first andsecond mounting brackets 3200 and 3300 via suitable fasteners (notshown) to maintain the spacing between these components.

3.2 Drum Assembly

The flexible capture member 5000 may be wound onto and off of the drumassembly 3500. As best shown in FIG. 9G, the drum assembly 3500 includesa drum 3510 having a cylindrical exterior surface 3510 a and acylindrical interior surface 3510 b; a first drum flange 3512 having acircular exterior surface 3512 a, a circular interior surface 3512 b, acylindrical perimeter surface 3512 c, and a cylindrical mounting surface3512 d that defines a mounting opening through the first flange 3512; asecond drum flange 3514 having a circular exterior surface 3514 a, acircular interior surface 3514 b, a cylindrical perimeter surface 3514c, and a cylindrical mounting surface 3514 d that defines a mountingopening through the second flange 3514; a drum shaft 3520; a coupler3532 including a tubular coupler shaft 3532 a defining a shaft-receivingbore therethrough and a coupler flange 3532 b extending radiallyoutwardly from the coupler shaft 3532 a; a first annular flange 3534; asecond annular flange 3536; and a third annular flange 3537.

The first and second drum flanges 3512 and 3514 are fixedly attached toopposing longitudinal ends (not labeled) of the drum 3510 via fasteners(not shown) such that the interior surface 3510 b of the drum 3510 andthe interior surfaces 3512 b and 3514 b of the first and second drumflanges 3512 and 3514 define a cylindrical inner drum cavity (notlabeled).

The coupler flange 3532 b and the first annular flange 3534 are fixedlyattached to one another and to the first drum flange 3512 via fasteners(not shown) such that: (1) the coupler flange 3532 b contacts theexterior surface 3512 a of the first drum flange 3512; (2) the firstannular flange 3534 is within the inner drum cavity and contacts theinterior surface 3512 b of the first drum flange 3512; (3) the couplerflange 3532 b and the first annular flange 3534 sandwich part of thefirst drum flange 3512 therebetween; and (4) a first portion of thecoupler shaft 3532 a is within the inner drum cavity while a secondportion of the coupler shaft 3532 a is outside of the inner drum cavity.

The second annular flange 3536 and the third annular flange 3538 arefixedly attached to one another and to the second drum flange 3514 viafasteners (not shown) such that: (1) the third annular flange 3538contacts the exterior surface 3514 a of the second drum flange 3514; (2)the second annular flange 3536 is within the inner drum cavity andcontacts the interior surface 3514 b of the second drum flange 3514; and(3) the second annular flange 3536 and the third annular flange 3538sandwich part of the second drum flange 3514 therebetween.

The drum shaft 3520 extends across the inner drum cavity such that afirst end 3520 a of the drum shaft 3520 is received in theshaft-receiving bore defined through the coupler shaft 3532 a and asecond end 3520 b of the drum shaft 3520 is outside of the inner drumcavity. The drum shaft 3520 is coupled to the coupler 3532 in anysuitable manner such that the drum shaft 3520 is substantially axiallyfixed (i.e., cannot substantially move axially) relative to the coupler3532 and such that the drum shaft 3520 and the coupler 3532 rotatetogether about the longitudinal axis of the drum shaft 3520. That is,the drum shaft 3520 and the coupler 3532 are coupled such that rotationof the drum shaft 3520 causes the coupler 3532 to rotate, andvice-versa. In this embodiment, this coupling is achieved via a fastener(not shown) threadably received by the coupler 3532 and the drum shaft3520. This fixedly attaches the coupler 3532 and the drum shaft 3520. Inother embodiments, the drum shaft is keyed to the coupler (orvice-versa) such that they rotate together. In other embodiments,retaining rings, pins, clips, or other elements axially fix the drumshaft relative to the coupler.

The drum shaft 3520 is mounted to the second mounting bracket 3300.Specifically, the second end 3520 b of the drum shaft 3520 extendsthrough the second mounting opening defined through the second mountingbracket 3300 and is received in a drum shaft flange bearing 3910attached to the second mounting bracket 3300. This enables the drumshaft 3520 to rotate about its longitudinal axis relative to the secondmounting bracket 3300. The drum shaft 3520 is mounted to the firstmounting bracket 3200 via the below-described coupling of the coupler3532 and a motor output shaft 7358 a of a hydraulic motor 7358 of thehydraulic system 7300.

3.3 Level Wind System

The level wind system 3600 ensures that the flexible capture member 3600is wound onto (and off of) the drum 3510 in a generally uniform manner.As best shown in FIG. 9F, the level wind system 3600 includes a levelwind shaft 3610, a first traveler 3620, a second traveler 3630, a guideshaft 3640, a first pulley 3650, a second pulley 3660, and a belt 3670.

The first and second travelers 3620 and 3630 are slidably mounted to thelevel wind shaft 3610 in a spaced-apart fashion such that theirrespective guide elements (not shown) are received in channels (notlabeled) defined in the exterior surface of the level wind shaft 3610around its circumference. The arrangement and shape of these groovesdefine how far and how fast the first and second travelers 3620 and 3630slide back and forth relative to the level wind shaft 3610 as the levelwind shaft 3610 rotates. The first and second travelers 3620 and 3630are also slidably mounted to the guide shaft 3640 to prevent the firstand second travelers 3620 and 3630 from about the longitudinal axis ofthe level wind shaft 3610.

The level wind shaft 3610 is mounted to the sides 3102 and 3104 of theanchor system base 3100. More specifically, the ends of the level windshaft 3610 are received in respective level wind shaft flange bearings(not labeled) attached to the sides 3102 and 3104 of the anchor systembase 3100 such that the level wind shaft 3610 can rotate about itslongitudinal axis relative to the sides 3102 and 3104 of the anchorsystem base 3100. Similarly, the guide shaft 3400 is mounted to thesides 3102 and 3104 of the anchor system base 3100. More specifically,the ends of the guide shaft 3640 are received in respective guide shaftflange bearings (not labeled) attached to the sides 3102 and 3104 of theanchor system base 3100 such that the guide shaft 3640 can rotate aboutits longitudinal axis relative to the sides 3102 and 3104 of the anchorsystem base 3100.

The first pulley 3650 is mounted to and coupled to the level wind shaft3610 in any suitable manner such that the first pulley 3650 issubstantially axially fixed (i.e., cannot substantially move axially)relative to the level wind shaft 3610 and such that the first pulley3650 and the level wind shaft 3610 rotate together about thelongitudinal axis of the level wind shaft 3610. That is, the firstpulley 3650 and the level wind shaft 3610 are coupled such that rotationof the first pulley 3650 causes the level wind shaft 3610 to rotate, andvice-versa. In this embodiment, this coupling is achieved via a fastener(not shown) threadably received by the first pulley 3650 and the levelwind shaft 3610. This fixedly attaches the first pulley 3650 to thelevel wind shaft 3610. In other embodiments, the level wind shaft iskeyed to the first pulley (or vice-versa) such that they rotatetogether. In other embodiments, retaining rings, pins, clips, or otherelements axially fix the first pulley relative to the level wind shaft.

As best shown in FIG. 9G, the second pulley 3660 is mounted to andcoupled to the drum shaft 3520 in any suitable manner such that thesecond pulley 3660 is substantially axially fixed (i.e., cannotsubstantially move axially) relative to the drum shaft 3520 and suchthat the second pulley 3660 and the drum shaft 3520 rotate togetherabout the longitudinal axis of the drum shaft 3520. That is, the secondpulley 3660 and the drum shaft 3520 are coupled such that rotation ofthe drum shaft 3520 causes the second pulley 3660 to rotate, andvice-versa. In this embodiment, this coupling is achieved via a fastener(not shown) threadably received by the second pulley 3660 and the drumshaft 3520. This fixedly attaches the second pulley 3660 to the drumshaft 3520. In other embodiments, the drum shaft is keyed to the secondpulley (or vice-versa) such that they rotate together. In otherembodiments, retaining rings, pins, clips, or other elements axially fixthe second pulley relative to the drum shaft.

The belt 3670 fits around and operatively connects the first and secondpulleys 3650 and 3660 such that rotation of one of the pulleys causesthe other to rotate.

In operation, as the drum shaft 3520 of the drum assembly 3500 rotates,the second pulley 3660 rotates therewith. Rotation of the second pulley3660 causes the first pulley 3650 to rotate due to their connection viathe belt 3670. Rotation of the first pulley 3650 causes the level windshaft 3610 to rotate. Rotation of the level wind shaft 3610 causes thefirst and second travelers 3620 and 3630 to slide relative to the levelwind shaft 3610 due to their guide elements being received in thegrooves defined in the level wind shaft 3610. This sliding of the firstand second travelers 3620 and 3630 (which is keyed to rotation of thedrum shaft 3520) guides placement of the flexible capture member 5000 asit is wound onto (or off of) the drum 3510.

3.3 Transition Assembly

The transition assembly 3700 is configured to route the flexible capturemember 5000 from the aircraft-landing structure 8000 to the level windsystem 3600. As best shown in FIG. 9C, the transition assembly 3700includes a first transition assembly housing portion 3710, a secondtransition assembly housing portion 3720, a transition pulley 3730, anda fastener 3740. The first and second transition assembly housingportions 3710 and 3720 are attachable to one another via the fastener3740, and together define a transition pulley cavity and a flexiblecapture member receiving bore in fluid communication with the transitionpulley cavity. The transition pulley 3730 is rotatably mounted on aspindle (not labeled) within the transition pulley cavity such that thetransition pulley 3730 can rotate relative to the first and secondtransition assembly housing portions 3710 and 3720. As described indetail below, the transition assembly 3700 is attachable to the lowersealing and mounting component 8500, which in turn is slidablyreceivable on the anchor system base 3100.

3.4 Hydraulic System

The hydraulic system 7300 is configured to regulate the tension in theflexible capture member 5000 during the fixed-wing aircraft retrievalprocess. As best shown in FIGS. 10A-10D, the hydraulic system 7300includes an electric hydraulic pump 7350 (such as one of the PU-SeriesHydraulic Economy Electric Pumps sold by Enerpac) having an inlet portand an outlet port, an accumulator 7352 (such as the Piston-StyleHydraulic Accumulator #6716K51 sold by McMaster-Carr) having aninlet/outlet port, a pressure relief valve 7356 (such as the AdjustableStainless Steel Relief Valve #5027K11 sold by McMaster-Carr) having aninlet port and an outlet port, the hydraulic motor 7358 (such as thePilot Flange Mount J Series Hydraulic Motor #5PZL3 sold by Grainger)having an inlet port and an outlet port, a hydraulic fluid tank 7362(such as that included in one of the PU-Series Hydraulic EconomyElectric Pumps sold by Enerpac) having an inlet port and an outlet port,and a pressure switch 7364 (such as the Extended-Life Pressure Switch#4735K46 sold by McMaster-Carr).

The hydraulic motor 7358 is attached to the first mounting bracket 3200such that the motor output shaft 7358 a extends through the firstmounting opening defined through the first mounting bracket 3200 and isreceived in the shaft-receiving bore defined through the coupler shaft3532 a of the coupler 3532. The motor output shaft 7358 a is coupled tothe coupler 3532 in any suitable manner such that the motor output shaft7358 a and the coupler 3532 rotate together. That is, the motor outputshaft 7358 a and the coupler 3532 are coupled such that rotation of themotor output shaft 7358 a causes the coupler 3532 to rotate, andvice-versa. In this embodiment, the motor output shaft 7358 a is keyedto the coupler 3532.

The remaining components of the hydraulic system 7300 are attached toeach other; the container housing the anchor system 3000; and/or theanchor base 3100, the first mounting bracket 3200, or the secondmounting bracket 3300.

The inlet port of the electric hydraulic pump 7350 is in fluidcommunication with the outlet port of the tank 7362, and the outlet portof the electric hydraulic pump 7350 is in fluid communication with theinlet/outlet port of the accumulator 7352, the inlet port of thepressure relief valve 7356, and the inlet port of the hydraulic motor7358. The inlet port of the hydraulic motor 7358 is in fluidcommunication with the inlet port of the pressure relief valve 7356. Theoutlet port of the hydraulic motor 7358 is in fluid communication withthe outlet port of the pressure relief valve 7356 and the inlet port ofthe tank 7362. In this embodiment, these components are in fluidcommunication with one another via suitable flexible or rigid tubing(not shown), though any suitable lines, hoses, or tubing may be used tofluidically connect these components. The hydraulic system 7300 alsoincludes various fittings and connectors (not shown) that facilitatefluidically connecting these components. These fittings and connectorsare well-known in the art and are not described herein for brevity.

When electrically connected to a power source and powered on, theelectric hydraulic pump 7350 draws hydraulic fluid (such as oil or anyother suitable fluid) from the tank 7362 and through its inlet port andpumps the hydraulic fluid out of its outlet port at a pump outletpressure (800 psi in this example embodiment).

In certain situations, as explained below, the accumulator 7352 receiveshydraulic fluid at its inlet/outlet and stores hydraulic fluid at aparticular pressure to reduce pressure switch chatter (as describedbelow). The accumulator gas charge is preloaded to the pressure switchlower set point (650 psi in this example embodiment, as described below)to minimize pressure switch chatter frequency.

The pressure switch is configured to measure the pressure of hydraulicfluid at the accumulator 7352. The pressure switch 7364 selectivelyconnects the electric hydraulic pump 7350 to a power source 7400 basedon the pressure P1 of hydraulic fluid at the accumulator 7352. Thepressure switch measures P1 and: (1) electrically connects the powersource 7400 and the electric hydraulic pump 7350 when P1 is less than apressure switch lower set point (650 psi in this example embodiment);and (2) electrically disconnects the power source 7400 and the electrichydraulic pump 7350 when P1 is greater than or equal to a pressureswitch upper set point (800 psi in this example embodiment). Thecombination of the accumulator 7352 and the pressure switch 7364 ensuresthat the electric hydraulic pump 7350 only operates as needed tomaintain the pressure of the hydraulic fluid in the accumulator 7352.

The pressure relief valve 7356 receives hydraulic fluid at its inletport and prevents the hydraulic fluid from exiting its outlet port untilthe pressure of the hydraulic fluid reaches a pressure relief valve setpoint (850 psi in this example embodiment). In other words, the pressurerelief valve 7356 is movable between a closed configuration in which thepressure relief valve 7356 prevents the hydraulic fluid from flowingfrom its inlet port to its outlet port and an open configuration inwhich the pressure relief valve 7356 enables the hydraulic fluid to flowfrom its inlet port to its outlet port. The pressure relief valve 7356is biased to the closed configuration, and moves to the openconfiguration when the pressure of the hydraulic fluid reaches thepressure relief valve set point.

Depending on the scenario, the hydraulic motor 7358 receives hydraulicfluid at either its inlet port from the electric hydraulic pump 7350 orits outlet port from the pressure relief valve 7356. When the hydraulicmotor 7358 receives hydraulic fluid at its inlet port from the electrichydraulic pump 7350, the hydraulic fluid flows through the hydraulicmotor 7358 and exits its outlet port. The flow of the hydraulic fluid inthis direction causes the output shaft of the hydraulic motor 7358 torotate in a direction that, as described below, causes the flexiblecapture member to wrap around the drum 3510. On the other hand, whenexcessive force on the flexible capture member 5000 forces the drum 3510to rotate in a manner that enables flexible capture member payout, thehydraulic motor 7358 receives hydraulic fluid at its outlet port fromthe pressure relief valve 7356, and the hydraulic fluid flows throughthe hydraulic motor 7358 and exits its inlet port. The flow of thehydraulic fluid in this direction is intentionally lossy, forming anenergy sink for the kinetic energy of the aircraft being captured.

3.4.1 Flexible Capture Member Haul-in Phase

FIG. 10A is a schematic block diagram of part of the hydraulic system7300 during the flexible capture member haul-in phase (sometimes calledthe “haul-in phase” for brevity) of the fixed-wing aircraft retrievalprocess. The haul-in phase is defined for the purposes of this sectionas occurring when the force F_(DRUM) the drum 3510 imposes on theflexible capture member (via the torque the hydraulic motor 7358 exertson the coupler 3532) exceeds any force F_(OPPOSING) imposed on theflexible capture member 5000 that opposes F_(DRUM) (such as when theflexible capture member is slack below a recently captured fixed-wingaircraft or when the multicopter is descending following capture of thefixed-wing aircraft).

During the haul-in phase, the pressure P1 of the hydraulic fluid at theaccumulator 7352 is or falls below the 650 psi pressure switch lower setpoint. Accordingly, the pressure switch 7364 electrically connects theelectric hydraulic pump 7350 to the power source 7400. The electrichydraulic pump 7350 draws hydraulic fluid from the tank 7362 and pumpsthe hydraulic fluid at the pump outlet pressure to the inlet/outlet portof the hydraulic accumulator 7352, the inlet port of the pressure reliefvalve 7356, and the inlet port of the hydraulic motor 7358.

Since at this point the pressure P1 of the hydraulic fluid at theaccumulator 7352 is less than the 800 psi pressure switch upper setpoint, the pressure switch 7364 continues electrically connecting theelectric hydraulic pump 7350 to the power source 7400 throughout thehaul-in phase.

Since the pressure P1 at the accumulator 7352 is less than the 850 psipressure relief valve set point, the pressure relief valve 7356 preventsthe hydraulic fluid from flowing through it.

The hydraulic fluid instead flows through the hydraulic motor 7358 andexits the outlet port of the hydraulic motor 7358. The flow of thehydraulic fluid through the hydraulic motor 7358 in this direction(i.e., from inlet port to outlet port) causes the output shaft of thehydraulic motor 7358 to exert a counter-clockwise (from the viewpoint ofFIG. 10A) torque on the coupler 3532, which transmits that torque to thedrum shaft 3520, which transmits that torque to the drum flanges 3512and 3514, which transmits that torque to the drum 3510. This torqueimposes a force F_(DRUM) on the flexible capture member 5000 via thedrum 3510. Since the force F_(OPPOSING) on the flexible capture member5000 is less than F_(DRUM), the torque the hydraulic motor 7358 exertson the coupler 3532 causes the drum 3510 to rotate counter-clockwise(from the viewpoint of FIG. 10A) relative to the anchor system base3100. This causes the flexible capture member 5000 to wrap around thedrum 3510 (and decrease the amount of flexible capture member 5000extending between the drum 3510 and the multicopter 10)).

The hydraulic fluid flows from the outlet port of the hydraulic motor7358 to the inlet port of the tank 7362.

In this example embodiment, the components and set points are sized,shaped, arranged, set, or otherwise configured such that F_(DRUM) isabout 80 pounds during the haul-in phase.

3.4.2 Neutral Phase

FIGS. 10B and 10C are schematic block diagrams of part of the hydraulicsystem 7300 during the flexible capture member neutral phase (sometimesreferred to as the “neutral phase” for brevity) of the fixed-wingaircraft retrieval process. The neutral phase is defined for thepurposes of this section as occurring when the force F_(DRUM) the drum3510 imposes on the flexible capture member (via the torque thehydraulic motor 7358 exerts on the coupler 3532) equals a forceF_(OPPOSING) imposed on the flexible capture member 5000 that opposesF_(DRUM) (such as when the multicopter is station-keeping above theanchor system in preparation for fixed-wing aircraft retrieval).

During the neutral phase, the drum 3510 does not rotate relative to theanchor system base 3100. Even so, hydraulic fluid leaks through thehydraulic motor 7358 and drains into the tank 7362. The accumulator 7352eliminates the need to constantly run the electric hydraulic pump 7350during the neutral phase in response to this leakage and ensure F_(DRUM)remains constant to regulate the tension in the flexible capture member5000.

As shown in FIG. 10B, once F_(OPPOSING) equals F_(DRUM), the electrichydraulic pump 7350 continues to operate because P1 is less than the 650psi pressure switch lower set point. But since hydraulic fluid flowthrough the hydraulic rotor 7358 has been reduced to mere leakage,pressure P1 begins to build and the accumulator 7352 begins charging. Asshown in FIG. 10C, once the pressure P1 reaches the 800 psi pressureswitch upper set point, the accumulator 7352 is charged and the pressureswitch 7364 electrically disconnects the electric hydraulic pump 7350from the power source 7400. The accumulator 7352 begins discharging toreplenish the hydraulic fluid leaking through the hydraulic motor 7358.Once the pressure P1 falls below the 650 psi pressure switch lower setpoint, the pressure switch 7364 electrically connects the electrichydraulic pump 7350 to the power source 7400 to again charge theaccumulator 7352. The use of the accumulator 7352 and the pressureswitch 7364 therefore ensures that leakage through the hydraulic motor7358 is accounted for and that F_(DRUM) will not decrease as hydraulicfluid leaks through the hydraulic motor 7358.

In this example embodiment, the components and set points are sized,shaped, arranged, set, or otherwise configured such that F_(DRUM) isabout 80 pounds during the neutral phase.

3.4.3 Flexible Capture Member Payout Phase

FIG. 10D is a schematic block diagram of part of the hydraulic system7300 during the flexible capture member payout phase (sometimes referredto as the “payout phase” for brevity) of the fixed-wing aircraftretrieval process. The payout phase is defined for the purposes of thissection as occurring when the force F_(DRUM) the drum 3510 imposes onthe flexible capture member (via the torque the hydraulic motor 7358exerts on the coupler 3532) is less than a force F_(OPPOSING) imposed onthe flexible capture member 5000 that opposes F_(DRUM) (such as when themulticopter is climbing to prepare for fixed-wing aircraft retrieval orjust after the fixed-wing aircraft captures and begins to deflect theflexible capture member).

During the payout phase, F_(OPPOSING) causes the drum 3510 to spinclockwise (from the viewpoint of FIG. 10D) and pay out flexible capturemember 5000 wrapped around the drum 3510 (and increase the amount offlexible capture member 5000 extending between the drum 3510 and themulticopter 10). This clockwise spinning of the drum 3510 forceshydraulic fluid to flow into the outlet port of the hydraulic motor7358, through the hydraulic motor 7358, and exit the inlet port of thehydraulic motor 7358. Since hydraulic fluid cannot enter the outlet portof the electric hydraulic pump 7350, this causes the pressure P1 of thehydraulic fluid at the accumulator 7352 to increase. Once the pressureP1 reaches the 850 psi pressure relief valve set point, the pressurerelief valve 7356 enables hydraulic fluid to flow through it. Thiscauses hydraulic fluid to flow from the inlet port of the hydraulicmotor 7358 to the inlet port of the pressure relief valve 7356 and fromthe outlet port of the pressure relief valve 7356 to the outlet port ofthe hydraulic motor 7358 until the drum 3510 stops rotating clockwise(from the viewpoint of FIG. 10D) and P1 drops below the 850 psi pressurerelief valve set point.

During the payout phase, hydraulic fluid does not necessarily drain tothe tank 7362, and the electric hydraulic pump 7350 thus doesn't need toreplenish any drained hydraulic fluid. This means that P1 will not dropbelow the 650 psi pressure switch lower set point, and the pressureswitch 7364 electrically disconnects the electric hydraulic pump 7350from the power source 7400 during most (if not all) of the payout phase.

Accordingly, the relative positioning and configuration of thecomponents of the hydraulic system enable the hydraulic motor to spin ineither direction while maintaining torque on the drum shaft in thedesired direction (counter-clockwise in the embodiment show in FIGS.10A-10D) to maintain F_(DRUM) on the flexible capture member

In this example embodiment, F_(DRUM) is controlled by the pressurerelief valve set point (the higher the set point, the higher F_(DRUM))and friction. In this example embodiment, F_(DRUM) is about 85 poundsduring the payout phase (i.e., greater than F_(DRUM) in the haul-in andneutral phases)

4. Aircraft-Landing Structure

Controlling the multicopter 10 post-capture to lower the fixed-wingaircraft 20 a to the ground (or another non-compliant structure) risksdamaging the fixed-wing aircraft 20 a. For instance, the multicopter 10could descend too quickly or stall while descending and drop, causingthe fixed-wing aircraft 20 a to impact the ground at high speed. Even aslow and well-controlled descent of the multicopter 10 could coincidewith poorly timed pendulum swing of the fixed-wing aircraft 20 a,resulting in damage when the fixed-wing aircraft 20 a touches down onthe surface.

In certain situations, a compliant aircraft-landing structure 8000 isemployed to gently receive the fixed-wing aircraft 20 a post-capture andhold it in place above the ground (or other non-compliant surface) in agenerally secure manner to facilitate retrieval at a later point. Theuse of this compliant aircraft-landing structure 8000 minimizespotential impact damage to the fixed-wing aircraft 20 a and enables themulticopter 10 to land the fixed-wing aircraft 20 a on theaircraft-landing structure 8000 and then land itself a safe distanceaway.

FIGS. 11A-11M illustrate one example embodiment of the aircraft-landingstructure 8000 and its components, which include: an inflatableaircraft-supporting body 8100; multiple gussets 8105; a tubular spacerguide 8110; spaced-apart cylindrical inflatable supports 8200 a, 8200 b,8200 c, and 8200 d; a guiding assembly 8300 including a spacer 8310 andan upper guiding component 8400 and an intermediate guiding component8500 attached to the spacer 8310; an inflation device 8600; a deflationdevice 8700; and a lower guiding and mounting component 8800.

The aircraft-supporting body 8100 is formed from one or more pieces offabric material (such as nylon, polyester, dacron, vinyl, or othercomposite laminate sheets) that are stitched, adhered, or otherwisefastened together in an airtight manner to generally form afrustoconical shape when inflated. The gussets 8105 and the tubularspacer guide 8110 are made of similar material. As best shown in FIGS.11E-11G, the tubular spacer guide 8110 is attached to theaircraft-supporting body 8100 in a suitable manner (such as viastitching or adhesive) near its top and extends from there into theinterior of the aircraft-supporting body 8100. The gussets 8105 areattached to and extend radially between the spacer guide 8110 and aninner surface 8100 a of the aircraft-supporting body 8100. These gussets8105 and the spacer guide 8110 assist in maintaining the guidingassembly 8300 upright when the aircraft-supporting body 8100 isinflated.

Each support 8200 a-8200 d is formed from one or more pieces of material(such as any of those listed above) that are stitched, adhered, orotherwise fastened together in an airtight manner to generally formcylinders when inflated. The supports are attached to the underside ofthe aircraft-supporting body 8100 via stitching, adhesive, or any othersuitable manner. The interiors of the supports 8200 a-8200 d are influid communication with the interior of the aircraft-supporting body8100 to enable fluid (e.g., air) to flow among these components. Thisenables the aircraft-supporting body 8100 and the supports 8200 a-8200 dto be inflated via a single inflator attached to the inflation device8600. The supports 8200 a-8200 d have dumbbells 8205 a-8025 drespectively attached thereto. The dumbbells 8205 a-8205 d add weight tothe supports 8200 a-8200 d to help maintain the aircraft-landingstructure 8000 upright as the fixed-wing aircraft 20 a contacts theflexible capture member 5000, as described below. The dumbbells may bereplaced with any suitable components that add weight to the supports.In one embodiment, the supports are partially filled with material, suchas sand, to weigh them down. In other embodiments, stakes are used toanchor the supports to the ground instead of or in addition to weightedelements.

As best shown in FIGS. 11E-11G, the spacer 8310 of the guiding assembly8300 extends through the spacer guide 8110 such that a first end 8310 aof the spacer 8310 is external to the aircraft-supporting body 8100 andan opposing second end 8310 b of the spacer 8310 is inside of theinterior of the aircraft-supporting body 8100. Hose clamps (not labeled)or any other suitable devices clamp the upper portion 8100 a of theaircraft-supporting body 8100 and the spacer guide 8110 to the exteriorcylindrical surface 8310 c of the spacer 8310 to attach these componentsto one another. The spacer 8310 includes a cylindrical interior surface8310 d that defines a flexible capture member receiving bore. The upperguiding component 8400 is attached to the first end 8310 a of the spacer8310 via suitable fasteners, and the intermediate guiding component 8500is attached to the second end 8310 b of the spacer 8310 via suitablefasteners.

As best shown in FIGS. 11H and 11I, the upper guiding component 8400includes a tubular body 8410, a tubular mounting element 8420, lower andupper roller bearings 8430 a and 8430 b, a retaining element 8440, aneedle bearing supporter 8450, and multiple needle bearings 8460.

The body 8410 defines a cylindrical interior surface 8412 that forms aflexible capture member receiving bore therethrough. The mountingelement 8420 surrounds part of the body 8410. The upper roller bearing8430 b surrounds part of the body 8410 and is positioned between anupper surface (not labeled) of the mounting element 8420 and a lip (notlabeled) of the body 8410. The lower roller bearing 8430 a surroundspart of the body 8410 and is positioned between a lower surface (notlabeled) of the mounting element 8420 and the retaining element 8440,which is disposed within a channel defined around the circumference ofthe body 8410. The retaining element 8440 retains the body 8410, themounting element 8420, and the roller bearings 8430 a and 8430 b inplace relative to one another. The needle bearing supporter 8450 isattached to the body 8410 via fasteners, and the needle bearings 8460are rotatably attached to the needle bearing supporter 8450 such thatthey can rotate relative to the needle bearing supporter 8450.

The mounting element 8420 of the upper guiding component 8400 is fixedlyattached to the first end 8310 a of the spacer 8310 of the guidingassembly 8300 via one or more fasteners. After attachment, the rollerbearings 8430 a and 8430 b enable the body 8410 and the attached needlebearing supporter 8450 and needle bearings 8460 to rotate together aboutthe longitudinal axis of the body 8410 relative to the mounting element8430 and the guiding assembly 8300.

As best shown in FIGS. 11J and 11K, the intermediate guiding component8500 includes a body 8510 having an inner surface 8512. Moving from topto bottom in FIG. 11K, the inner surface 8512 tapers radially inwardlyinto a cylindrical shape and then tapers back radially outwardly. Theinner surface 8512 defines a flexible capture member receiving bore. Thebody 8510 is fixedly attached to the second end 8310 b of the spacer8310 of the guiding assembly 8300 via one or more fasteners.

As best shown in FIGS. 11L and 11M, the lower guiding and mountingcomponent 8800 includes a transition assembly receiving component 8810connected to an anchor system base mounting component 8830. Thetransition assembly receiving component 8810 is generally cylindricaland includes an exterior cylindrical aircraft-landing structureattachment surface 8813 and interior cylindrical surfaces 8814 and 8818.An annular lip 8816 that extends radially outwardly from the cylindricalsurface 8818 separates the interior cylindrical surfaces 8814 and 8818.The interior cylindrical surface 8814 defines a flexible capture memberreceiving bore, and the interior cylindrical surface 8818 defines atransition assembly receiving bore.

The anchor system base mounting component 8830 includes an upper portion8832 and a lower portion 8834 spaced apart by a middle portion 8836. Themiddle portion 8836 is partially recessed radially inward relative tothe upper and lower portions 8832 and 8834. This defines an anchorsystem base receiving channel (not labeled). As best shown in FIG. 11E,hose clamps (not labeled) clamp a lower portion (not labeled) of theaircraft-supporting body 8100 to the aircraft-landing structureattachment surface 8813 of the transition assembly receiving component8810 to attach these components to one another. The transition assemblyreceiving bore receives part of the transition assembly 3700 in thetransition assembly receiving bore, and a fastener is used to attach thetransition assembly 3700 to the transition assembly receiving bore. Onceattached, the flexible capture member receiving bore of the lowerguiding and mounting component 8800 is in fluid communication with theflexible capture member receiving bore of the transition assembly 3700.The lower guiding and mounting component 8800 is attached to the anchorsystem base 3100 via the anchor system base receiving channel. That is,the anchor system base 3100 slidably receives the lower guiding andmounting component 8800. A fastener may be used to further secure theseelements together.

As best shown in FIG. 11D, the inflation device 8600 is attached to(such as via stitching, adhesive, or in any other suitable manner) andextends downward from the underside of the aircraft-supporting body8100. The inflation device 8600 is in fluid communication with theinterior of the aircraft-supporting body 8100 (which is in fluidcommunication with the interiors of the supports 8200 a-8200 d). Theinflation device 8600 is sized, positioned, and otherwise configured tobe attached to a suitable inflator (such as via a hose clamp or anyother suitable manner of attachment) to enable inflation of theaircraft-supporting body 8100 and the supports 8200 and 8300 asdescribed below.

As best shown in FIG. 11D, the deflation device 8700 is located on theunderside of the aircraft-supporting body 8100. The deflation device8700 includes a deflation element, such as a removable cap or a valve,that is switchable between a deflation configuration in which thedeflation element enables air to flow out of the aircraft-supportingbody 8100 and a sealed configuration in which the deflation element doesnot enable air to flow out of the aircraft-supporting body 8100. Thedeflation device 8700 enables an operator to quickly deflate theaircraft-supporting body 8100 and the supports 8200 a-8200 d withminimal effort, such as by removing a cap or opening a valve.

In another embodiment, the aircraft-landing structure does not includethe intermediate guiding element. In this embodiment, the upper guidingelement and the lower guiding and mounting element are attached toopposing ends of the spacer such that the spacer extends between theupper guiding element and the lower guiding and mounting element.

In another embodiment, the anchor system base threadably receives thelower guiding and mounting component.

In other embodiments, the aircraft-supporting body includes stabilizingribs extending along its tapered walls. In further embodiments, thebottom of the aircraft-supporting body is stiff in bending.

In another embodiment, a plurality of tension members are attached toand extend between the interior of the aircraft-supporting body and theouter surface of the flexible capture member receiving tube. Thesetension members help support the weight/tension of the flexible capturemember receiving tube and help maintain the apex of the aircraft-landingstructure erect.

In certain embodiments, tie-downs (such as ropes, bungees, and the like)may be used to secure the aircraft-landing structure to the ground or toa suitable base structure, such as the above-described aircraft systembase.

In other embodiments, the aircraft-supporting body is formed fromcompliant rods rather than inflatable tubes.

5. Flexible Capture Member

As best shown in FIGS. 12D-12G, the flexible capture member 5000 isattachable to the multicopter 10 and the anchor system 3000 andthreadable through the aircraft-landing structure 8000 to facilitateretrieval of the fixed-wing aircraft 20 a from free, wing-borne flight.The flexible capture member may be a rope (such as a Spectra rope) orother similar element.

In some embodiments, the flexible capture member includes an elasticportion, such as a bungee or similar element, at the end attachable tothe multicopter. The elastic portion may be rigged such that a portionof the strain energy is directed into a damping element such as a metalring or a one-way pulley. By rigging the elastic portion as a compliantdamper (as opposed to a spring), more energy is absorbed during capture,and undesirable ricochet is minimized.

In some embodiments, the flexible capture member includes a captureportion that is thicker near its ends (such as within 12 feet of eachend) that it is in its center. In one embodiment, both ends of thecapture portion terminate in a Brummel eye splice in which the buriedtails constitute the thicker portion of the capture portion.

In some embodiments in which the flexible capture member includes arope, the flexible capture member includes an elastic member inside thecore of the rope. The elastic member shortens the rope as it slackensand is wound onto the drum. During payout, the elastic member allows therope to lengthen as it leaves the drum, and a lossy payout device isformed.

6. Accessories Container and Other Components

As best shown in FIG. 9H, the anchor system 3000 is attached to thecontainer bottom 4000 a of an anchor system and accessory storagecontainer to enable easy and compact storage of the anchor system 3000and various accessories, such as (but not limited to): a generator; theflexible capture member 5000; an R/C transmitter stand that helpsenforce geo-referenced joystick commands of the R/C controller; a fireextinguisher; shovels; hard hats. Further, certain components of thehydraulic system 7300 are attached to the container bottom 4000 a.

7. Methods of Operation

As described in detail below: (1) the multicopter 10 and the storage andlaunch system 2000 are usable to facilitate launch of the fixed-wingaircraft 20 a into free, wing-borne flight; and (2) the multicopter 10,the anchor system 3000, the flexible capture member 5000, and theaircraft-landing structure 8000 are usable to facilitate retrieval ofthe fixed-wing aircraft 20 a from free, wing-borne flight.

7.1 Multicopter-Assisted Fixed-Wing Aircraft Launch Method

The multicopter-assisted fixed-wing aircraft launch method begins withthe multicopter 10 disassembled and stored in the storage and launchsystem 2000, as best shown in FIG. 8A. The multicopter operator unpacksthe 13 modules and moves the launch-assist assembly 2100 of the storageand launch system 2000 to its launch position, as best shown in FIG. 8C.

The multicopter operator (or the fixed-wing aircraft operator) mountsthe fixed-wing aircraft 20 a to the launch-assist assembly 2100 by: (1)disengaging the safety mechanism 2150 of the fuselage-retaining assembly2130, which enables the pincers 2132 and 2134 to separate from thefuselage-retaining orientation to the fuselage-release orientation; (2)lowering the fuselage of the fixed-wing aircraft 20 a between thepincers 2132 and 2134 (the fact that the safety mechanism 2150 isdisengaged enables weight of the fixed-wing aircraft to force thepincers 2132 and 2134 to separate to receive the fuselage); (3)positioning the wings of the fixed-wing aircraft 20 a on the wingengaging surfaces 2121 a and 2123 a of the aircraft engaging bracket2120 of the launch-assist assembly 2100; and (4) engaging the safetymechanism 2150, which prevents the pincers 2132 and 2134 from separatingto the fuselage-release position and retains the fuselage of thefixed-wing aircraft 20 a between the pincers 2132 and 2134. FIG. 8Dshows the fixed-wing aircraft 20 a mounted to the launch-assist assembly2100 in this manner.

The multicopter operator (or the fixed-wing aircraft operator) selectsthe appropriate cooling nozzle for the engine cooling system for thefixed-wing aircraft 20 a. The multicopter operator attaches that coolingnozzle to the engine cooling system and hangs the engine cooling systemon the back of the aircraft engaging bracket 2120 of the launch-assistassembly 2100 such that the engine of the fixed-wing aircraft 20 a is inthe cooling nozzle's path.

The multicopter operator switches on an idle power circuit of themulticopter 10 to perform various preflight checks, such as operatingmode status checks, throttle response checks, attitude indicatorresponse checks, heading accuracy checks, R/C range checks, and thelike. Switching on the idle power circuit does not power the rotormotors. The idle power circuit thus enables the multicopter operator toconduct most preflight checks without having to worry about accidentallyswitching on one or more of the rotor motors.

The multicopter operator then attaches the hub module 100 to thefixed-wing aircraft 20 a by: (1) operating the cam servo motor 381(either manually or remotely via the R/C controller) to rotate the cam350 to the attached rotational position (clockwise from this viewpoint);(2) operating the lock servo motor 391 (either manually or remotely viathe R/C controller) to rotate the lock servo arm 392 into the camrotation-preventing rotational position (clockwise from this viewpoint)such that the lock servo motor locking extension 392 a on the end of thelock servo arm 392 engages the cam servo motor arm lock device 382 a ofthe cam servo motor arm 382; and (3) seating a rearwardly curved hook 21attached to the fuselage of the fixed-wing aircraft 20 a on the cam 350such that hook generally rests on the ridge 351 of the cam 350 and thetip of the hook is disposed in the valley 353 of the cam 350. FIG. 12Ashows the hub module 100 attached to the fixed-wing aircraft 20 a.

At this point the fixed-wing aircraft 20 a is attached to the cam 350(and the hub base 100), the fuselage of the fixed-wing aircraft 20 acontacts the front and rear aircraft engaging brackets 340 a and 340 b(to prevent rotation about the pitch and yaw axes of the fixed-wingaircraft 20 a), and the stabilizers 290 a and 290 b contact the wings ofthe fixed-wing aircraft 20 a (to prevent rotation about the roll axis ofthe fixed-wing aircraft 20 a).

Since the lock servo motor locking extension 392 a is engaged to the camservo motor arm lock device 382 a of the cam servo motor arm 382, thecam servo motor 381 cannot rotate the cam 350 from the attachedrotational position to the release rotational position(counter-clockwise from this viewpoint). This prevents undesired releaseof the fixed-wing aircraft 20 a from the cam 350 (and thus themulticopter 10).

After the hub module 100 is attached to the fixed-wing aircraft 20 a,the multicopter operator: (1) attaches the front and rear landing gearmodules 600 a to 600 d to their respective front and rear landing gearextension modules 500 a to 500 d; (2) attaches the front and rearlanding gear extension modules 500 a to 500 d to their respective rotorarm modules 400 a to 400 d; and (3) attaches and locks the rotor armmodules 400 a to 400 d to the hub module 100 to complete assembly of themulticopter 10.

The multicopter operator ensures the front and rear landing gear modules600 a to 600 d are not in the path of rotation of the rotors of theircorresponding rotor arm modules 400 a to 400 b, and connects the mainpower line of the multicopter 10. Unlike the idle power circuit, themain power lines are capable of delivering current sufficient to drivethe rotor motors and cause the multicopter 10 to fly.

The multicopter operator begins the engine start-up procedure for thefixed-wing aircraft 20 a. The multicopter operator selects the ALTHOLDflight mode for the multicopter 10. The multicopter operator (or anassistant) disengages the safety mechanism 2150 of thefuselage-retaining assembly 2130, which enables the pincers 2132 and2134 to separate from the fuselage-retaining orientation to thefuselage-release orientation.

The multicopter operator advances the throttle to begin verticallyclimbing and lift the fixed-wing aircraft 20 a from between the pincers2132 and 2134 (which are free to separate and release the fuselage ofthe fixed-wing aircraft 20 a since the safety mechanism 2150 isdisengaged). Once the multicopter 10 and attached fixed-wing aircraft 20a have reached a designated altitude, the multicopter operator controlsthe multicopter 10 to begin dashing forward. At this point, if theairspeed, GPS reception, and pitch angle of the fixed-wing aircraft 20 ais within a suitable range (e.g., 10 to 20 degrees), the multicopter 10can release the fixed-wing aircraft 20 a.

Releasing the fixed-wing aircraft 20 a from the cam 350 (and themulticopter 10) is a two-step process, as shown in FIGS. 12B and 12C. Torelease the fixed-wing aircraft 20 a from the cam 350 (and thus themulticopter 10), the multicopter operator first remotely controls thelock servo motor 391 (via the R/C controller) to rotate the lock servoarm 392 into the cam rotation-enabling rotational position(counter-clockwise from this viewpoint). Second, the multicopteroperator remotely controls the cam servo motor 381 (via the R/Ccontroller) to rotate the cam 350 from the attached rotational positionto the release rotational position (counter-clockwise from thisviewpoint). As shown in the progression from FIG. 12B to FIG. 12C, asthe cam servo motor 381 rotates the cam 350 from the attached rotationalposition to the release rotational position, the valley 352 and theascending edge of the ridge 353 forces the hook 21 off of the cam 350,thereby releasing the fixed-wing aircraft 20 a from the cam 350 (and themulticopter 10).

After release, the multicopter operator may switch the multicopter 10 tohalf-power mode and recover the multicopter 10 either manually viaALTHOLD and/or LOITER flight modes or semi-autonomously via RTL flightmode.

7.2 Multicopter-Assisted Fixed-Wing Aircraft Retrieval Method

FIGS. 12D-12G diagrammatically show retrieval of the fixed-wing aircraft20 a from free, wing-borne flight via use of the multicopter 10, theanchor system 3000, the flexible capture member 5000, and theaircraft-landing structure 8000. FIG. 12H is a graph 7900 of thepressure P1 of the hydraulic fluid at the accumulator 7352 of thehydraulic system 7300 over time during the fixed-wing aircraft retrievalprocess. For simplicity, in this example embodiment P1 is assumed to be0 psi at time T0.

To retrieve the fixed-wing aircraft 20 a from free, wing-borne flight,the anchor system operator positions the anchor system 3000 at aretrieval location. Before time T0, while the electric hydraulic pump7350 is switched off, the anchor system operator pulls some of theflexible capture member 5000 off of the drum 3510 and feeds it throughthe level wind system 3600 and around the transition pulley 3730 of thetransition assembly 3700. From there, the anchor system operator feedsthe flexible capture member 5000 through the flexible capture memberreceiving bores of the transition assembly 3700, the lower guiding andmounting component 8800, the intermediate guiding component 8500, andthe upper guiding component 8400 such that the free end of the flexiblecapture member 5000 exits the upper guiding component 8400. The anchorsystem operator then attaches the free end of the flexible capturemember 5000 to the hub module 100 of the multicopter 10 in a suitablemanner. Since the flexible capture member 5000 is slack between the drum3510 and the multicopter 10, F_(OPPOSING) is negligible at time T0. Theanchor system operator activates a blower (not shown) to inflate theaircraft-landing structure 8000.

At time T0, the anchor system operator switches the electric hydraulicpump 7350 on to begin a haul-in phase of the fixed-wing aircraftretrieval process to take up the slack in the flexible capture member5000. Since P1 is 0 psi—i.e., less than the 650 psi pressure switchlower set point—the pressure switch 7364 electrically connects the powersource 7400 and the electric hydraulic pump 7350. As described above,the electric hydraulic pump 7350 pumps hydraulic fluid at the 800 psipump outlet pressure to drive the hydraulic motor 7358 to rotate thedrum 3510 counter-clockwise (from the viewpoint in FIG. 10A) and take upthe slack in the flexible capture member 5000.

At time T1, all of the slack in the flexible capture member 5000 haswound around the drum 3510, and F_(OPPOSING) equals F_(DRUM). Thisbegins a neutral phase of the fixed-wing aircraft retrieval processbefore multicopter climb. Flow through the hydraulic motor 7358 slows tomere leakage, and electric hydraulic pump 7350 begins charging theaccumulator 7352. Once P1 reaches the 800 psi pressure switch upper setpoint, the pressure switch 7364 electrically disconnects the powersource 7400 and the electric hydraulic pump 7350. The accumulator 7352begins discharging in response to for the hydraulic fluid leakingthrough the hydraulic motor 7358. The pressure switch 7364 continuesalternating between electrically connecting and electricallydisconnecting the power source 7400 and the electric hydraulic pump 7350during the neutral phase so P1 alternates between 650 and 800 psi.

At time T2, the multicopter operator begins controlling the multicopter10 to ascend to a retrieval position above the anchor system 3000. Thisbegins a payout phase of the fixed-wing aircraft retrieval process. Theclimbing multicopter 10 exerts a force F_(OPPOSING) on the flexiblecapture member 5000 that exceeds F_(DRUM), which causes the drum 3510 tospin clockwise (from the viewpoint in FIG. 10D) and payout the flexiblecapture member 5000. As described above, this increases P1 to (or evenabove) the 850 psi pressure relief valve set point. Once the multicopter10 reaches its desired height (just before time T3), the multicopteroperator controls the multicopter 10 to stop climbing and beginstation-keeping relative to the anchor system 3000. Since F_(OPPOSING)equals F_(DRUM), P1 decreases to 800 psi.

At time T3, as shown in FIG. 12D, the multicopter operator controls themulticopter 10 to station-keep relative to the anchor system 3000, atwhich point F_(OPPOSING) equals F_(DRUM). This begins a neutral phase ofthe fixed-wing aircraft retrieval process, described above with respectto T1 through T2.

At time T4, as shown in FIG. 12E, the fixed-wing aircraft operatorcontrols the fixed-wing aircraft 20 a to contact and capture part of theflexible capture member 5000 extending between the multicopter 10 andthe drum 3510. This begins a payout phase of the fixed-wing aircraftretrieval process. The impact of the fixed-wing aircraft 20 a on theflexible capture member 5000 exerts a force F_(OPPOSING) on the flexiblecapture member 5000 that exceeds F_(DRUM), which causes the drum 3510 tospin clockwise (from the viewpoint in FIG. 10D) and payout the flexiblecapture member 5000. As described above, this increases P1 to (or evenabove) 850 psi—i.e., the pressure relief valve set point. In the payoutphase, P1 maintains its 850 psi value as of time T4. Once the movementof the fixed-wing aircraft 20 a has dampened such that F_(OPPOSING) nolonger exceeds F_(DRUM) (just before time T5), P1 decreases to 800 psi.

At time T5, as shown in FIG. 12F, the multicopter operator controls themulticopter 10 to descend toward the aircraft-landing structure 8000,and there is slack in the flexible capture member 5000 extending betweenthe captured fixed-wing aircraft 20 a and the drum 3510. Accordingly,F_(OPPOSING) is less than F_(DRUM), and the haul-in phase begins, asdescribed above for time T0 through T1.

At time T6, as shown in FIG. 12G, after the fixed-wing aircraft 20 a hasreached and is resting on the aircraft-landing structure 8000, themulticopter operator controls the multicopter 10 to hover, andF_(OPPOSING) equals F_(DRUM). This begins a neutral phase of thefixed-wing aircraft retrieval process, described above with respect toT1 through T2. The multicopter operator controls the multicopter 10 toland clear of the aircraft-landing structure 8000 and the fixed-wingaircraft 20 a.

The hydraulic system 7300 of the anchor system 3000 is configured toensure the fixed-wing aircraft 20 a remains atop the aircraft landingstructure 8000. For this to happen, the force F_(DRUM) must be greaterthan the weight of the fixed-wing aircraft 20 a. In this exampleembodiment, the fixed-wing aircraft 20 a weighs about 60 pounds whileF_(DRUM) is about 80 pounds in the neutral phase, so the hydraulicsystem ensures the fixed-wing aircraft 20 a remains atop the aircraftlanding structure 8000.

Additionally, the aircraft landing structure 8000 is sized, shaped, andinflated at a suitable pressure to support the fixed-wing aircraft 20 awithout buckling or tipping over to ensure that the fixed-wing aircraft20 a does not fall to the ground. In this example embodiment, a 0.3 psiinflation pressure is used along with inflatable supports that have 1200square inch footprints such that each inflatable support can supportabout 360 pounds without buckling. The fixed-wing aircraft 20 a weighsabout 60 pounds, so the inflatable supports are more than able tosupport the fixed-wing aircraft 20 a even under severe wind loadingconditions. For instance, even a 30 mph wind pushing sideways on theaircraft-landing structure would apply a maximum compression of 100pounds on a leeward inflatable support (assuming 50 pound weights areused to weigh each inflatable support down, as described above). Thisplus the 60 pound fixed-wing aircraft's weight is well below the 360pound maximum.

The anchor system 3000 is therefore configured to quickly andautomatically modify its operation to regulate the force F_(DRUM)applied to the flexible capture member as the fixed-wing aircraftretrieval process switches between the haul-in, neutral, and payoutphases.

8. Alternative Hydraulic System

FIGS. 13A-13D illustrate part of a second embodiment of the hydraulicsystem 7300 a that includes: (1) the electric hydraulic pump 7350; (2)the accumulator 7352; (3) a pressure regulator 7354 (such as theHydraulic Pressure Regulator #9474T11 sold by McMaster-Carr) having aninlet port and an outlet port; (4) the pressure relief valve 7356; (5)the hydraulic motor 7358; (6) a check valve 7360 (such as the SuperHigh-Pressure Check Valve #5010K63 sold by McMaster-Carr) having aninlet port and an outlet port; (7) the hydraulic fluid tank 7362; and(8) the pressure switch 7364.

The inlet port of the electric hydraulic pump 7350 is in fluidcommunication with the outlet port of the tank 7362, and the outlet portof the electric hydraulic pump 7350 is in fluid communication with theinlet/outlet port of the accumulator 7352 and the inlet port of thepressure regulator 7354. The outlet port of the pressure regulator 7354is in fluid communication with the inlet port of the pressure reliefvalve 7356 and the inlet port of the hydraulic motor 7358. The inletport of the hydraulic motor 7358 is in fluid communication with theinlet port of the pressure relief valve 7356. The outlet port of thehydraulic motor 7358 is in fluid communication with the outlet port ofthe pressure relief valve 7356 and the inlet port of the check valve7360. The outlet port of the check valve 7360 is in fluid communicationwith the inlet port of the tank 7362. In this embodiment, thesecomponents are in fluid communication with one another via suitableflexible tubing (not shown), though any suitable lines, hoses, or tubingmay be used to fluidically connect these components. The hydraulicsystem 7300 a also includes various fittings and connectors (not shown)that facilitate fluidically connecting these components. These fittingsand connectors are well-known in the art and are not described hereinfor brevity.

When electrically connected to a power source and powered on, theelectric hydraulic pump 7350 draws hydraulic fluid (such as oil or anyother suitable fluid) from the tank 7362 and through its inlet port andpumps the hydraulic fluid out of its outlet port at a pump outletpressure (800 psi in this example embodiment).

In certain situations, as explained below, the accumulator 7352 receiveshydraulic fluid at its inlet/outlet and stores hydraulic fluid at aparticular pressure to reduce pressure switch chatter (as describedbelow). The accumulator gas charge is preloaded to the pressure switchlower set point (800 psi in this example embodiment, as described below)to minimize pressure switch chatter frequency.

The pressure switch is configured to measure the pressure of hydraulicfluid at the accumulator 7352. The pressure switch 7364 selectivelyconnects the electric hydraulic motor 7350 to a power source 7400 basedon the pressure P1 of hydraulic fluid at the accumulator 7352. Thepressure switch measures P1 and: (1) electrically connects the powersource 7400 and the electric hydraulic pump 7350 when P1 is less thanthe pressure switch lower set point (800 psi in this exampleembodiment); and (2) electrically disconnects the power source 7400 andthe electric hydraulic pump 7350 when P1 is greater than or equal to apressure switch upper set point (1,000 psi in this example embodiment).The combination of the accumulator 7352 and the pressure switch 7364ensures that the electric hydraulic pump 7350 only operates as needed tomaintain the pressure of the hydraulic fluid in the accumulator 7352.

The pressure regulator 7354 receives hydraulic fluid at its inlet port.If the pressure of the hydraulic fluid is greater than a pressureregulator set point (800 psi in this example embodiment), the pressureregulator 7354 reduces the pressure of the hydraulic fluid to the 800psi pressure regulator set point and enables the reduced-pressurehydraulic fluid to exit its outlet port at this precisely tuned pressureregulator set point. If the pressure of the hydraulic fluid received atthe inlet port is less than the 800 psi pressure regulator set point,the pressure regulator 7354 enables the hydraulic fluid to flow throughit and exit its outlet port without substantially changing the pressure.

The pressure relief valve 7356 receives hydraulic fluid at its inletport and prevents the hydraulic fluid from exiting its outlet port untilthe pressure of the hydraulic fluid reaches a pressure relief valve setpoint (850 psi in this example embodiment) that is greater than the 800psi pressure regulator set point, as described above.

Depending on the scenario, the hydraulic motor 7358 receives hydraulicfluid at either its inlet port from the pressure regulator 7354 or itsoutlet port from the pressure relief valve 7356. When the hydraulicmotor 7358 receives hydraulic fluid at its inlet port from the pressureregulator 7354, the hydraulic fluid flows through the hydraulic motor7358 and exits its outlet port. The flow of the hydraulic fluid in thisdirection causes the output shaft of the hydraulic motor 7358 to rotatein a direction that, as described below, causes the flexible capturemember to wrap around the drum 3510. On the other hand, when excessiveforce on the flexible capture member forces the drum 3510 to rotate in amanner that enables flexible capture member payout, the hydraulic motor7358 receives hydraulic fluid at its outlet port from the pressurerelief valve 7356, and the hydraulic fluid flows through the hydraulicmotor 7358 and exits its inlet port. The flow of the hydraulic fluid inthis direction is intentionally lossy, forming an energy sink for thekinetic energy of the aircraft being captured.

The check valve 7360 receives hydraulic fluid at its inlet port andenables the hydraulic fluid to exit its outlet port, but preventshydraulic fluid (or air) from flowing from its outlet port to its inletport. In other embodiments, the tension-regulating flexible capturemember payout and retract device does not include the check valve 7360.

8.1 Flexible Capture Member Haul-in Phase

FIG. 13A is a schematic block diagram of part of the hydraulic system,7300 a during the haul-in phase of the fixed-wing aircraft retrievalprocess.

During the haul-in phase, initially, the pressure P1 of the hydraulicfluid at the accumulator 7352 is below the 800 psi pressure switch lowerset point. Accordingly, the pressure switch 7364 electrically connectsthe electric hydraulic pump 7350 to the power source 7400. The electrichydraulic pump 7350 draws hydraulic fluid from the tank 7362 and pumpsthe hydraulic fluid at the pump outlet pressure to the inlet/outlet portof the hydraulic accumulator 7352 and the inlet port of the hydraulicpressure regulator 7354.

Since at this point the pressure P1 of the hydraulic fluid at theaccumulator 7352 is less than the 800 psi pressure switch lower setpoint, the pressure switch 7364 continues electrically connecting theelectric hydraulic pump 7350 to the power source 7400 throughout thehaul-in phase.

The pressure regulator 7354 enables the hydraulic fluid it receives fromthe electric hydraulic pump 7350 to flow through it. The hydraulic fluidflows from the outlet port of the pressure regulator 7354 to the inletport of the pressure relief valve 7356 and the inlet port of thehydraulic motor 7358. Since the pressure P2 of the hydraulic fluiddownstream of the pressure regulator 7354 and upstream of the pressurerelief valve 7356 and the hydraulic motor 7358 is less than the 850 psipressure relief valve set point, the pressure relief valve 7356 preventsthe hydraulic fluid from flowing through it.

The hydraulic fluid instead flows from the outlet port of the pressureregulator 7354 to the inlet port of the hydraulic motor 7358, throughthe hydraulic motor 7358, and exits the outlet port of the hydraulicmotor 7358. The flow of the hydraulic fluid through the hydraulic motor7358 in this direction (i.e., from inlet port to outlet port) causes theoutput shaft of the hydraulic motor 7358 to exert a counter-clockwise(from the viewpoint of FIG. 13A) torque on the drum shaft. This torqueimposes a force F_(DRUM) on the flexible capture member 5000 via thedrum 3510. Since the force F_(OPPOSING) on the flexible capture member5000 is less than F_(DRUM), the torque the hydraulic motor 7358 exertson the drum shaft causes the drum shaft and the drum 3510 to rotatecounter-clockwise (from the viewpoint of FIG. 13A) relative to theanchor system base. This causes the flexible capture member 5000 to wraparound the drum 3510 (and decrease the amount of flexible capture member5000 extending between the drum 3510 and the multicopter 10).

The hydraulic fluid flows from the outlet port of the hydraulic motor7358 to the inlet port of the check valve 7360, and exits the outletport of the check valve 7360 into the inlet port of the tank 7362.

In this example embodiment, the components and set points are sized,shaped, arranged, set, or otherwise configured such that F_(DRUM) isabout 80 pounds during the haul-in phase.

8.2 Neutral Phase

FIGS. 13B and 13C are schematic block diagrams of part of the hydraulicsystem 7300 a during the neutral phase of the fixed-wing aircraftretrieval process.

In the neutral phase, the drum 3510 does not rotate relative to theanchor system base. Even so, hydraulic fluid leaks through the hydraulicmotor 7358 and drains through the check valve 7360 and into the tank7362. The accumulator 7352 eliminates the need to constantly run theelectric hydraulic pump 7350 during the neutral phase in response tothis leakage and ensure F_(DRUM) remains constant to regulate thetension in the flexible capture member.

As shown in FIG. 13B, once F_(OPPOSING) equals F_(DRUM), the electrichydraulic pump 7350 continues to operate because P1 is less than the 800psi pressure switch lower set point. But since hydraulic fluid flowthrough the hydraulic rotor 7358 has been reduced to mere leakage,pressure P1 begins to build and the accumulator 7352 begins charging. Asshown in FIG. 13C, once the pressure P1 reaches the 1,000 psi pressureswitch upper set point, the accumulator 7352 is charged and the pressureswitch 7364 electrically disconnects the electric hydraulic pump 7350from the power source 7400. The accumulator 7352 begins discharging toreplenish the hydraulic fluid leaking through the hydraulic motor 7358.Once the pressure P1 falls below the 800 psi pressure switch lower setpoint, the pressure switch 7364 electrically connects the electrichydraulic pump 7350 to the power source 7400 to again charge theaccumulator 7352. The use of the accumulator 7352 and the pressureswitch 7364 therefore ensures that leakage through the hydraulic motor7358 is accounted for and that F_(DRUM) will not decrease as hydraulicfluid leaks through the hydraulic motor 7358.

In this example embodiment, the components and set points are sized,shaped, arranged, set, or otherwise configured such that F_(DRUM) isabout 80 pounds during the neutral phase.

8.3 Flexible Capture Member Payout Phase

FIG. 13D is a schematic block diagram of part of the tension-regulatingflexible capture member payout and retract device 7300 during the payoutphase of the fixed-wing aircraft retrieval process.

In the payout phase, F_(OPPOSING) causes the drum 3510 to spin clockwise(from the viewpoint of FIG. 13D) and pay out flexible capture memberwrapped around the drum 3510. This clockwise spinning of the drum 3510forces hydraulic fluid to flow into the outlet port of the hydraulicmotor 7358, through the hydraulic motor 7358, and exit the inlet port ofthe hydraulic motor 7358. Since hydraulic fluid cannot enter the outletport of the pressure regulator 7354, this causes the pressure P2 of thehydraulic fluid downstream of the pressure regulator 7354 and upstreamof the pressure relief valve 7356 and the hydraulic motor 7358 toincrease. Once the pressure P2 of the hydraulic fluid downstream of thepressure regulator 7354 and upstream of the pressure relief valve 7356and the hydraulic motor 7358 reaches the 850 psi pressure relief valveset point, the pressure relief valve 7356 enables hydraulic fluid toflow through it. This causes hydraulic fluid to flow from the inlet portof the hydraulic motor 7358 to the inlet port of the pressure reliefvalve 7356 and from the outlet port of the pressure relief valve 7356 tothe outlet port of the hydraulic motor 7358 until the drum 3510 stopsrotating clockwise (from the viewpoint of FIG. 13D) and P2 drops belowthe pressure relief valve set point (850 psi in this example embodiment)(i.e., until F_(OPPOSING) falls below F_(DRUM)).

During the payout phase, hydraulic fluid does not drain to the tank7362, and the electric hydraulic pump 7350 thus doesn't need toreplenish any drained hydraulic fluid. This means that P1 will not dropbelow the 800 psi pressure switch lower set point, and the pressureswitch 7364 electrically disconnects the electric hydraulic pump 7350from the power source 7400 during most (if not all) of the payout phase.

Accordingly, the relative positioning and configuration of thecomponents of the hydraulic system enable the hydraulic motor to spin ineither direction while maintaining torque on the drum shaft in thedesired direction (counter-clockwise in the embodiment show in FIGS.13A-13D) to maintain F_(DRUM) on the flexible capture member

In this example embodiment, F_(DRUM) is controlled by the pressurerelief valve set point (the higher the set point, the higher F_(DRUM))and friction. In this example embodiment, F_(DRUM) is about 85 poundsduring the payout phase.

8.4 Example Fixed-Wing Aircraft Capture Process

FIG. 13E is a graph 7900 of the pressure P1 of the hydraulic fluid atthe accumulator 7352 and the pressure P2 of the hydraulic fluiddownstream of the pressure regulator 7354 and upstream of the pressurerelief valve 7356 and the hydraulic motor 7358 over time during thefixed-wing aircraft retrieval process. For simplicity, in this exampleembodiment P1 and P2 are assumed to be 0 psi at time T0.

Before time T0, while the electric hydraulic pump 7350 is switched off,the anchor system operator pulls some of the flexible capture member5000 off of the drum 3510 and attaches the flexible capture member 5000to the multicopter. Since the flexible capture member is slack betweenthe drum 3510 and the multicopter, F_(OPPOSING) is negligible at timeT0.

At time T0, the anchor system operator switches the electric hydraulicpump 7350 on to begin a haul-in phase of the fixed-wing aircraftretrieval process to take up the slack in the flexible capture member5000. Since P1 is 0 psi—i.e., less than the 800 psi pressure switchlower set point—the pressure switch 7364 electrically connects the powersource 7400 and the electric hydraulic pump 7350. As described above,the electric hydraulic pump 7350 pumps hydraulic fluid at the 100 psipump outlet pressure to drive the hydraulic motor 7358 to rotate thedrum 3510 counter-clockwise (from the viewpoint in FIG. 13A) and take upthe slack in the flexible capture member 5000. P2 and P1 are generallyequal in the haul-in phase (though P2 may be slightly lower than P1 dueto pressure loss via the tubing and connectors).

At time T1, all of the slack in the flexible capture member 5000 haswound around the drum 3510, and F_(OPPOSING) equals F_(DRUM). Thisbegins a neutral phase of the fixed-wing aircraft retrieval processbefore multicopter climb. Flow through the hydraulic motor 7358 slows tomere leakage, and electric hydraulic pump 7350 begins charging theaccumulator 7352. When P1 reaches 1,000 psi pressure switch upper setpoint, the pressure switch 7364 electrically disconnects the powersource 7400 and the electric hydraulic pump 7350. The accumulator 7352begins discharging in response to the hydraulic fluid leaking throughthe hydraulic motor 7358. The pressure switch 7364 continues alternatingbetween electrically connecting and electrically disconnecting the powersource 7400 and the electric hydraulic pump 7350 during the neutralphase so P1 alternates between 800 and 1,000 psi. P2 tracks P1 untilreaching the 800 psi pressure regulator set point.

At time T2, the multicopter operator begins multicopter climb, whichbegins a payout phase of the fixed-wing aircraft retrieval process. Theclimbing multicopter exerts a force F_(OPPOSING) on the flexible capturemember 5000 that exceeds F_(DRUM), which causes the drum 3510 to spinclockwise (from the viewpoint in FIG. 13D) and payout the flexiblecapture member 5000. As described above, this increases P2 to (or evenabove) the 850 psi pressure relief valve set point. In the payout phase,P1 maintains its 1,000 psi value as of time T2. Once the multicopterreaches its desired height (just before time T3), it stops climbing andbegins station-keeping. Since F_(OPPOSING) equals F_(DRUM), P2 decreasesto 800 psi.

At time T3, the multicopter is station-keeping and F_(OPPOSING) equalsF_(DRUM). This begins a neutral phase of the fixed-wing aircraftretrieval process, described above with respect to T1 through T2.

At time T4, the fixed-wing aircraft contacts and captures the flexiblecapture member 5000 extending between the multicopter and the drum 3510.This begins a payout phase of the fixed-wing aircraft retrieval process.The impact of the fixed-wing aircraft on the flexible capture member5000 exerts a force F_(OPPOSING) on the flexible capture member 5000that exceeds F_(DRUM), which causes the drum 3510 to spin clockwise(from the viewpoint in FIG. 13D) and payout the flexible capture member5000. As described above, this quickly increases P2 to (or even above)850 psi—i.e., the pressure relief valve set point. In the payout phase,P1 maintains its 1,000 psi value as of time T4. Once the movement of thefixed-wing aircraft has dampened such that F_(OPPOSING) no longerexceeds F_(DRUM) (just before time T5), P2 decreases to 800 psi.

At time T5, there is slack in the flexible capture member 5000 extendingbetween the captured fixed-wing aircraft and the drum 3510. Accordingly,F_(OPPOSING) is less than F_(DRUM), and the haul-in phase begins, asdescribed above for time T0 through T1.

At time T6, the fixed-wing aircraft has reached and is resting on theaircraft-landing structure, and F_(OPPOSING) equals F_(DRUM). Thisbegins a neutral phase of the fixed-wing aircraft retrieval process,described above with respect to T1 through T2.

The tension-regulating flexible capture member payout and retract device7300 is therefore configured to quickly and automatically modify itsoperation to regulate the force F_(DRUM) applied to the flexible capturemember as the fixed-wing aircraft retrieval process switches between thehaul-in, neutral, and payout phases.

8.5 Variations

As generally described above, the sizing and configuration of thecomponents of the hydraulic system along with the different pressure setpoints result in the example F_(DRUM) for the different phases of thefixed-wing aircraft retrieval process. One may vary the sizing andconfiguration of the components or the different pressure set points toachieve a desired F_(DRUM) for the different phases of the fixed-wingaircraft retrieval process.

In various embodiments, a stopper is attached to a suitable position ofthe flexible capture member between the anchor system and themulticopter. The stopper is sized to not fit through the one of thecomponents of the aircraft-landing structure or one of the components ofthe anchor system, and therefore partitions the flexible capture memberinto a portion that can be wound onto the drum (the portion between thedrum and the stopper) and a portion that cannot be wound onto the drum(the portion between the stopper and the multicopter). One benefit isthat the stopper ensures that a length of slack flexible capture memberextends between the multicopter and the anchor system before themulticopter ascends for retrieval, which prevents the anchor system fromprematurely pulling on the multicopter. This length of slack flexiblecapture member also facilitates landing the multicopter after retrievalsince the multicopter will not have to fight against any force imposedby the anchor system.

In an alternative embodiment, the hydraulic system is instead anelectrically powered winch with a slipping clutch that operates in amanner similar to that of the hydraulic system described above toregulate the tension in the flexible capture member during thefixed-wing aircraft retrieval process. In this embodiment, theelectrically powered winch may include an electric motor having anoutput shaft, a drive shaft, a slipping clutch, a drum shaft, and adrum. The output shaft of the electric motor is operably connected tothe drive shaft in a suitable manner such that the electric motor drivesthe drive shaft. The slipping clutch, if included, is fixedly attachedto and rotatable with the drive shaft. If no clutch is present, theelectric motor may be forced to opposite its intended direction.Specifically, a brushed DC motor with a constant current electricalpower supply would enable the motor to spin either direction whilemaintaining torque in the desired direction for purpose of maintainingtension on the spool of flexible capture member.

The drum shaft is mounted to the anchor system base via suitablebearings so the drum shaft can freely rotate relative to the anchorsystem base. The drum is fixedly attached to and rotatable with the drumshaft. The slipping clutch is positioned adjacent the drum.

In operation, when the electric motor is powered on, the output shaft ofthe electric motor drives the drive shaft and the slipping clutch, andthe slipping clutch transmits torque to the drum and causes the drum torotate and exert a force F_(DRUM) on the flexible capture member asdescribed above. This continues as long as F_(OPPOSING) is less thanF_(DRUM). Once F_(OPPOSING) equals or exceeds F_(DRUM), the slippingclutch slips and enables the drum to payout flexible capture member. Todissipate payout energy, the clutch may be configured as an eddy currentbrake that regulates F_(DRUM). Since this slipping clutch processgenerates a substantial amount of heat, a cooling device, such as ablower or fan, may be employed to reduce operating temperatures.

9. Alternative Saddle

FIGS. 14A-14I show part of an alternative embodiment of the saddle 300 aand components thereof. The saddle 300 a is the portion of the hubmodule that: (1) the fixed-wing aircraft is attached to and releasedfrom to launch the fixed-wing aircraft into free, wing-borne flight; and(2) the flexible capture member is attached to for retrieval of thefixed-wing aircraft from free, wing-borne flight. This embodiment of thesaddle 300 a is sized, shaped, arranged, and otherwise configured toattach to and release the fixed-wing aircraft 20 b without requiring anymodification to the fixed-wing aircraft 20 b. The size, shape,arrangement, and configuration of the components of the saddle 300 a maybe modified such that the saddle 300 a can attach to and release otherfixed-wing aircraft (such as the fixed-wing aircraft 20 a).

The saddle 300 a includes a saddle base bracket 6310 and first andsecond saddle side brackets 6312 and 6314 straddling the saddle basebracket 6310. A cross-brace 6318 is connected to and extends between thefirst and second saddle side brackets 6312 and 6314 near their backends. As described in more detail below, the front ends of the firstsaddle side bracket 6312, the second saddle side bracket 6314, and thesaddle base bracket 6310 are connected or otherwise mounted to a frontengager 6320 such that the front engager 6320 can rotate relative to thefirst saddle side bracket 6312, the second saddle side bracket 6314, andthe saddle base bracket 6310. Although not shown for clarity, the saddlebase bracket 6310 is fixedly connected to the hub base via suitablemounting brackets, and the first and second saddle side brackets 6312and 6314 are fixedly connected to the hub base via suitable fasteners.

As best shown in FIGS. 14B and 14C, the front engager 6320 includes: ashaft 6321; first and second leading-edge engagers 6323 and 6326; sleevebearings 6322, 6324, 6325, and 6327; and a stabilizer 6328.

The first leading-edge engager 6323 includes a generally triangular base6323 a having a tube 6323 c extending therefrom. A shaft-receiving bore(not labeled) extends through the base 6323 a and the tube 6323 c. Thebase 6323 a defines a contoured leading edge engaging surface 6323 bthat is shaped to receive and engage the portion of the leading edge ofthe wing of the fixed-wing aircraft 20 b to which the saddle 300 a willattach, as described below. The base 6323 a includes a plurality ofstrengthening ribs extending outward from the tube 6323 c. Similarly,the second leading-edge engager 6326 includes a generally triangularbase 6326 a having a tube 6326 c extending therefrom. A shaft-receivingbore (not labeled) extends through the base 6326 a and the tube 6326 c.The base 6326 a defines a contoured leading edge engaging surface 6326 bthat is shaped to receive and engage the portion of the leading edge ofthe wing of the fixed-wing aircraft 20 b to which the saddle 300 a willattach, as described below. The base 6326 a includes a plurality ofstrengthening ribs extending outward from the tube 6326 c.

As noted above, the front engager 6230 is connected or otherwise mountedto the saddle base bracket 6310 and the first and second saddle sidebrackets 6312 and 6314 such that the front engager 6320 is rotatablerelative to those components. The saddle base bracket 6310 includes atubular mounting portion 6310 a that defines a shaft-receiving boretherethrough. Part of the shaft 6321 is received in the shaft-receivingbore of the tubular mounting portion 6310 a such that first and secondfree ends of the shaft are positioned on opposing sides of the tubularmounting portion 6310 a. The shaft 6321 is rotatably fixed relative tothe saddle base bracket 6310, though in other embodiments the shaft 6321may rotate relative to the saddle base bracket 6310. Suitable bearingsmay be incorporated at the interfaces between the saddle base bracketand the shaft to facilitate rotation of the shaft relative to the saddlebase bracket.

The first and second leading-edge engagers 6323 and 6326 are rotatablymounted to the shaft 6321 on opposite sides of the tubular mountingportion 6310 a of the saddle base bracket 6310 via the sleeve bearings6322, 6324, 6325, and 6327. Specifically, the sleeve bearings 6322 and6324 are press fit into the opposing ends of the shaft-receiving borethrough the first leading-edge engager 6323 such that the sleevebearings 6322 and 6324 cannot rotate relative to the first leading-edgeengager 6323. Part of the shaft 6321 is received in the sleeve bearings6322 and 6324 and the shaft-receiving bore of the first leading-edgeengager 6323 such that the first end of the shaft 6321 protrudes fromthe sleeve bearing 6324. The first end of the shaft 6321 is received ina first retaining element 6329 a fixedly attached to the second saddleside bracket 6314. The first retaining element 6329 a preventssubstantial axial movement of the shaft 6321 relative to the firstretaining nub 6329 a, and retains the first leading-edge engager 6323 onthe shaft 6321. At this point, the first leading-edge engager 6323 ismounted to the shaft 6321 via the sleeve bearings 6322 and 6324 suchthat the first leading-edge engager 6323 is rotatable about thelongitudinal axis of the shaft 6321 relative to the saddle base bracket6310. The longitudinal axis of the shaft 6321 is above the leading edgesof the wings of the fixed-wing aircraft 20 b.

Similarly, the sleeve bearings 6326 and 6325 are press fit into theopposing ends of the shaft-receiving bore through the secondleading-edge engager 6326 such that the sleeve bearings 6326 and 6325cannot rotate relative to the second leading-edge engager 6326. Part ofthe shaft 6321 is received in the sleeve bearings 6326 and 6325 and theshaft-receiving bore of the second leading-edge engager 6326 such thatthe second end of the shaft 6321 protrudes from the sleeve bearing 6325.The second end of the shaft 6321 is received in a second retainingelement 6329 b fixedly attached to the first saddle side bracket 6312.The second retaining element 6329 b prevents substantial axial movementof the shaft 6321 relative to the second retaining element 6329 a, andretains the second leading-edge engager 6326 on the shaft 6321. At thispoint, the second leading-edge engager 6326 is mounted to the shaft 6321via the sleeve bearings 6326 and 6325 such that the second leading-edgeengager 6326 is rotatable about the longitudinal axis of the shaft 6321relative to the saddle base bracket 6310.

The stabilizer 6328 is attached to the base 6323 a of the firstleading-edge engager 6323 and to the base 6326 a of the secondleading-edge engager 6326 such that the stabilizer 6328 extends betweenand connects the first and second leading-edge engagers 6323 and 6326.The stabilizer 6328 ensures the first and second leading-edge engagers6323 and 6326 rotate relative to the saddle base bracket 6310 and thefirst and second saddle side brackets 6312 and 6314 substantiallysimultaneously rather than independently of one another.

As best shown in FIGS. 14B and 14F, an aircraft attaching/releasingassembly 6340 is attached to the saddle base bracket 6310 and to thefront engager 6320 and controls rotation of the first engager 6320 aboutthe longitudinal axis of the shaft 6321 relative to the saddle basebracket 6310. As best shown in FIG. 14F, the aircraftattaching/releasing assembly 6340 includes: a front engager servo motor6345 having a front engager servo motor shaft 6345 a, a front engagerarm 6342, a front engager arm lock device 6342 a, a servo spacer 6344,first and second nut plates 6347 a and 6347 b, fasteners 6348 andcorresponding nuts 6348 a, a front engager rotation control link 6343having connectors 6343 a and 6343 b at opposite ends, a lock servo motor6341 having a lock servo motor shaft 6341 a, a lock arm 6346 terminatingat one end in a locking extension 6346 a, and first and second frontengager attachment brackets 6349 a and 6349 b.

The front engager servo motor 6345 and the lock servo motor 6341 areattached to one another and to the saddle base bracket 6310 via thefasteners 6348, the servo spacer 6344, the first and second nut plates6347 a and 6347 b, and the nuts 6348 a.

The front engager arm 6342 is attached near one end to the front engagerservo motor shaft 6345 a and near the other end to the connector 6343 a.The connector 6343 b is attached to the stabilizer 6328 of the frontengager 6320 via the first and second front engager attachment brackets6349 a and 6349 b (such as via suitable fasteners, not shown). Thisoperatively links the front engager servo motor shaft 6345 a to thefront engager 6320. The front engager arm lock device 6342 a is attachedto the front engager arm 6342 between the connector 6343 a and the frontengager servo motor shaft 6345 a.

The lock arm 6346 is attached to the lock servo motor shaft 6341 a nearone end. The free end of the lock arm 6346 terminates in the lockingextension 6346 a, which is engageable to the front engager arm lockdevice 6342 a in certain instances to prevent clockwise (from theviewpoint shown in FIGS. 14G-14I) rotation of the front engager arm6342.

The front engager servo motor 6345 controls rotation of the frontengager 6320 (and, specifically, the first and second leading-edgeengagers 6323 and 6326) about the longitudinal axis of the shaft 6321relative to the saddle base bracket 6310. To rotate the front engager6320, the front engager servo motor 6345 rotates the front engager servomotor shaft 6345 a, which rotates the attached front engager arm 6342,which in turn rotates the front engager 6320 via the front engagerrotation control link 6343. The front engager servo motor 6345 canrotate the front engager 6320 between an attached rotationalposition—shown in FIGS. 14G and 14H—and a release rotationalposition—shown in FIG. 14I.

The lock servo motor 6341 controls rotation of the lock arm 6346 betweena front engager rotation-preventing rotational position—shown in FIG.14G—and a front engager rotation-enabling rotational position—shown inFIGS. 14H and 14I. When the front engager 6320 is in the attachedrotational position and the lock arm 6346 is in the front engagerrotation-preventing rotational position, the locking extension 6346 aengages the front engager arm lock device 6342 a of the front engagerarm 6342. This prevents the front engager servo motor 6345 from rotatingthe front engager 6320 clockwise (from the viewpoint shown in FIGS.14G-14I) from the attached rotational position to the release rotationalposition. As best shown in FIG. 14G, the servo spacer 6344 preventscounter-clockwise rotation (from the viewpoint shown in FIGS. 14G-14I)of the front engager arm 6342.

FIGS. 14G-14I show how the front engager servo motor 6345 and the lockservo motor 6341 cooperate to rotate the front engager 6320 from theattached rotational position to the release rotational position.Initially, the front engager arm 6342 is in the attached rotationalposition and the lock arm 6346 is in the front engagerrotation-preventing rotational position. Here, the locking extension6346 a on the end of the lock arm 6346 engages the front engager armlock device 6342 a of the front engager arm 6342.

Since the locking extension 6346 a engages the front engager lock device6342 a of the front engager arm 6342, the front engager servo motor 6345cannot rotate the front engager 6320 from the attached rotationalposition to the release rotational position (clockwise from thisviewpoint). And as indicated above, the servo spacer 6344 b preventscounter-clockwise rotation of the front engager arm 6342 (from thisviewpoint).

Rotating the front engager 6320 from the attached rotational position tothe release rotational position is a two-step process. As shown in FIG.14H, the operator first operates the lock servo motor 6341 to rotate thelock arm 6346 into the front engager rotation-enabling rotationalposition (clockwise from this viewpoint). Second, as shown in FIG. 14I,the operator operates the front engager servo motor 6345 to rotate thefront engager 6320 from the attached rotational position to the releaserotational position (clockwise from this viewpoint).

As shown in FIG. 14B, separate (but in this embodiment, identical) rearengagers 6360 (here, trailing-edge engagers) are attached to the firstand second saddle side brackets 6312 and 6314. As best shown in FIGS.14D and 14E, the rear engager 6360 includes a body 6362 and a pivotableportion 6364 pivotably connected to the body 6362 via a suitable pivotshaft (not shown). The body 6362 includes a trailing edge engagingsurface 6362 a. The pivotable portion 6364 includes multiple surfacesthat define a trailing edge receiving channel 6364 a sized and shaped toreceive the trailing edge of a wing of the fixed-wing aircraft 20 b.Fasteners 6366 are threadably received in the pivotable portion 6364.The fasteners 6366 engage the top surface of the wing of the fixed-wingaircraft 20 b, and can be threaded further into or further out of thepivotable portion 6364 as desired to adjust clearance between thepivotable portion 6364 and the exterior upper surface of the wing. Inone embodiment, the fasteners are formed from a relatively softmaterial, such as Teflon, and the pivotable portion is formed from arelatively harder material, such as aluminum.

The body 6362 is fixedly attached to the appropriate saddle side bracketvia suitable fasteners (not shown for clarity) such that the trailingedge engaging surface 6362 a and the pivotable portion 6364 extend belowthe body 6362.

In operation, to launch the fixed-wing aircraft 20 b an operator firstattaches the hub module to the fixed-wing aircraft 20 b, assembles themulticopter, hoists the fixed-wing aircraft 20 b using the multicopterand brings it to a desired airspeed, and releases the fixed-wingaircraft 20 b from the multicopter, as generally described above.

For a multicopter including the saddle 300 a, the operator attaches thehub module to the fixed-wing aircraft 20 b by: (1) operating the frontengager servo motor 6345 (either manually or remotely via the R/Ccontroller) to rotate the front engager 6320 to the release rotationalposition; (2) inserting the trailing edges of the wings of thefixed-wing aircraft 20 b into the trailing edge receiving channels 6364a of the pivotable portions 6364 of the rear engagers 6360; (3)positioning the saddle 300 a relative to the fixed-wing aircraft 20 bsuch that the leading edge engaging surfaces 6323 b and 6326 b of thefront engager 6320 are adjacent the leading edges of the wings of thefixed-wing aircraft 20 b; (4) operating the front engager servo motor6345 (either manually or remotely via the R/C controller) to rotate thefront engager 6320 to the attached rotational position such that theleading edge engaging surfaces 6323 b and 6326 b of the front engager6320 contact the leading edges of the wings of the fixed-wing aircraft20 b; and (5) operating the lock servo motor 6341 (either manually orremotely via the R/C controller) to rotate the lock arm 6346 a into thefront engager rotation-preventing rotational position so the lockingextension 6346 a on the end of the lock arm 6346 engages the frontengager arm lock device 6342 a of the front engager arm 6342.

At this point the fixed-wing aircraft 20 b is attached to the saddle 300a (and the multicopter) because the front engager 6320 and the rearengagers 6360 engage the wings of the fixed-wing aircraft 20 btherebetween. The pivotable portions 6364 of the rear engagers 6360 arerotationally positioned relative to the bodies 6362 of the rear engagers6360 such that the trailing-edge engaging surfaces 6362 a are not withinthe trailing-edge receiving channels of the pivotable portions 6364. Thepositioning of the servo spacer 6344 b and the fact that the lockingextension 6346 a is engaged to the front engager arm lock device 6342 aof the front engager arm 6342 ensure the front engager servo motor 6345cannot rotate the front engager 6320 from the attached rotationalposition to the release rotational position. This prevents undesiredrelease of the fixed-wing aircraft 20 b from the saddle 300 a (and themulticopter).

Releasing the fixed-wing aircraft 20 b from the saddle 300 a while themulticopter is airborne is a two-step process. To release the fixed-wingaircraft 20 b from the saddle 300 a (and the multicopter), the operatorfirst remotely controls the lock servo motor 6341 (via the R/Ccontroller) to rotate the lock arm 6346 into the front engagerrotation-enabling rotational position. Second, the operator remotelycontrols the front engager servo motor 6345 (via the R/C controller) torotate the front engager 6320 from the attached rotational position tothe release rotational position. As the front engager servo motor 6345rotates the front engager 6320 from the attached rotational position tothe release rotational position, the first and second leading edgeengaging surfaces 6323 b and 6326 b of the front engager 6320 rotateaway from and begin to lose contact with the leading edge of the wing ofthe fixed-wing aircraft 20 b. As the front engager 6320 continues torotate clear of the wings of the fixed-wing aircraft 20 b, the pivotableportions 6364 of the rear engagers 6360 enable the fixed-wing aircraft20 b to freely pivot relative to the saddle base bracket 6310, the firstand second saddle side brackets 6312 and 6314, and the bodies 6362 ofthe rear engagers 6360 as gravity pulls the fixed-wing aircraft 20 bdownward. The center of gravity of the fixed-wing aircraft 20 a ispositioned forward of the rear engagers. As this occurs, the trailingedge engaging surfaces 6362 a of the bodies 6362 of the rear engagers6360 gradually enter the trailing-edge receiving channels of thepivotable portions 6364. As this occurs, the trailing-edge engagingsurfaces 6362 a contact the trailing edge of the wings and force themout of the trailing edge receiving channels, thus releasing thefixed-wing aircraft 20 a from the saddle 300 a (and the multicopter)into free flight.

As the fixed-wing aircraft 20 a rotates downward, its empennage risesrelative to the multicopter 10 as the nose of the fixed-wing aircraft 20a drops. The rear engagers are configured such that the trailing edgesof the wings of the fixed-wing aircraft 20 a are forced out of thetrailing edge receiving channels before the empennage of the fixed-wingaircraft 20 a contacts one of the rotors of the multicopter 10.

In another embodiment, the rear engagers include an ejector device (notshown) having an ejector plate movable from a loaded position to aneject position (and vice-versa). The ejector plate is biased to theeject position via a spring or other suitable biasing element. In thisembodiment, the act of clamping the wings of the fixed-wing aircraftbetween the front and rear engagers causes the trailing edges of thewings of the fixed-wing aircraft to contact the ejector plate andovercome the biasing force of the biasing element to move the ejectorplate to the loaded position, and hold it there while the wings areclamped. During release, once the front engager rotates clear of thewings, the biasing element moves the ejector plate from the loadedposition to the eject position. While this occurs, the ejector platecontacts the trailing edges of the wings and forces them away from thesaddle 300 a.

In the embodiment described above with respect to FIGS. 14A-14I, theleading edge engagers of the front engager rotate in a plane generallyparallel to a longitudinal axis of the fuselage of the fixed-wingaircraft to attach the fixed-wing aircraft to the saddle 300 a and torelease the fixed-wing aircraft from the saddle 300 a. In anotherembodiment, the leading edge engagers of the front engager rotate in aplane generally perpendicular to the longitudinal axis of the fuselageof the fixed-wing aircraft to attach the fixed-wing aircraft to thesaddle 300 a to and release the fixed-wing aircraft from the saddle 300a. For example, the free ends of the leading edge engagers may rotateinward, toward the fuselage, to move from the release rotationalposition to the attached rotational position and may rotate outward,away from the fuselage, to move from the attached rotational position tothe release rotational position.

In certain embodiments, the leading-edge engagers (and particularly theleading-edge engaging surfaces) are sized, shaped, arranged, andotherwise configured to force the nose of the fixed-wing aircraftdownward during release.

As noted above, this embodiment of the saddle 300 a may be sized,shaped, arranged, and otherwise configured to attach to and release anysuitable fixed-wing aircraft by clamping its wings between front andrear engagers. An operator could—without changing any other componentsof the multicopter—swap out one saddle base bracket, front engager, andrear engager combination (or the entire saddle including thosecomponents) configured for one type of aircraft with another saddle basebracket, front engager, and rear engager combination (or the entiresaddle including those components) configured for a different type ofaircraft. This adds yet another layer of modularity to the multicopterand enables it to carry many different types of fixed-wing aircraftwithout requiring any modification of those fixed-wing aircraft.

Various changes and modifications to the presently preferred embodimentsdescribed herein will be apparent to those skilled in the art. Thesechanges and modifications can be made without departing from the spiritand scope of the present subject matter and without diminishing itsintended advantages. It is intended that such changes and modificationsbe covered by the appended claims.

The invention claimed is:
 1. A method of retrieving an aircraft fromfree flight, the method comprising: flying a rotorcraft above an anchorsystem such that a first portion of a flexible capture member connectedat one end to the rotorcraft and at another end to the anchor systemextends between the rotorcraft and the anchor system; station-keepingthe rotorcraft relative to the anchor system such that the anchor systemexerts a first regulated force on the first portion of the flexiblecapture member; and after the aircraft has contacted and captured partof the first portion of the flexible capture member, thereby causing theanchor system to pay out a second portion of the flexible capture memberwhile exerting a second regulated force on the first and second portionsof the flexible capture member, descending the rotorcraft toward theanchor system.
 2. The method of claim 1, wherein descending therotorcraft toward the anchor system causes the anchor system to exertthe first regulated force on the first portion of the flexible capturemember, thereby causing the anchor system to retract at least some ofthe first portion of the flexible capture member.
 3. The method of claim1, further comprising descending the rotorcraft until the fixed-wingaircraft contacts an aircraft-landing structure.
 4. The method of claim3, further comprising inflating the aircraft-landing structure andpositioning the aircraft-landing structure such that the flexiblecapture member extends through the aircraft-landing structure betweenthe rotorcraft and the anchor system before the aircraft contacts theaircraft-landing structure after the aircraft has captured the part ofthe first portion of the flexible capture member.